diff --git a/book/real-world-software-development/chapter4/README.md b/book/real-world-software-development/chapter4/README.md
new file mode 100644
index 0000000..76c4be9
--- /dev/null
+++ b/book/real-world-software-development/chapter4/README.md
@@ -0,0 +1,66 @@
+## 문서 관리 시스템
+
+### 요구사항
+
+기존 환자 정보 파일을 읽어 색인을 추가하고 검색할 수 있는 형태의 정보로 변환
+
+문서의 형태 : 리포트, 우편물, 이미지
+
+각각의 문서는 관리 대상 파일의 경로와 어떤 환자의 기록물인지 나타내는 정보도 포함
+다양한 종류의 문서에서 특정 정보를 포함하는 문서를 검색해 찾기를 원함
+ex) Joe Bloggs를 포함하는 우편물 문서를 검색하면 그 결과를 반환해야한다.
+
+다른 종류의 문서도 추가할 수 있어야한다.
+
+
+### 설계 작업
+
+스위치 문의 문제점
+- 확장성 낮음, 다른 종류가 추가 될 때 마다 스위치문을 추가해야함.
+
+강한 형식의 원칙
+- 데이터 사용 방법을 규제함
+- 불변 객체를 활용하면, 오류가 발생 했을 때 오류가 발생하는 원인을 좁힐 수 있고, 불변성 덕분에 안전하게 문서를 색인하거나 캐싱할 수 있따.
+
+도메인 클래스 활용
+- 개념에 이름을 붙이고 수행할 수 있는 동작과 값을 제한함.
+- 발견성을 개선하고 버그 발생 범위를 줄일 수 있다.
+
+Map의 문제점
+- 유지보수성과 가독성을 떨어뜨림
+
+유비쿼터스 언어
+- 훌륭한 소프트웨어 개발팀은 유비쿼터스언어로 소프트웨어를 개발함.
+- 고객과 대화할 때 사용하는 용어를 응용프로그램의 코드와 같은 의미로 사용함.
+
+문자화 형식
+
+KISS 원칙
+
+리스코프 치환 원칙 : 클래스의 상속과 인터페이스 구현을 올바르게 사용하도록 도와줌.
+
+형식 : 클래스나 인터페이스
+하위 형식 : 두 형식이 부모와 자식 관계를 이룸
+
+1. 하위 형식에서 선행조건을 더할 수 없음. 부모가 지정한 것보다 더 많은 선행조건을 요구할 수 없음.
+2. 하위 형식에서 후행조건을 약화시킬 수 없음.
+3. 슈퍼 형식의 불변자는 하위 형식에서 보존됨.
+4. 히스토리 규칙
+
+is a 규칙
+
+코드를 재사용하기 위한 방법 세가지
+
+1. 유틸클래스
+2. 상속
+3. 도메인클래스
+
+유틸리티 클래스
+장점 : 가장 간단한다
+단점 : 시간이 흐를 수록 갓 클래스의 모양을 갖춰진다.
+
+상속 사용
+일반적으로 상속 관계를 통해 코드를 재사용하는 것은 올바른 방향이 아님.
+실제 관계를 반영한게 아니라 상속이 쉽게 깨질 수 있음.
+
+도메인 클래스 사용
diff --git a/book/real-world-software-development/chapter4/document-management/build.gradle.kts b/book/real-world-software-development/chapter4/document-management/build.gradle.kts
new file mode 100644
index 0000000..fdaa08f
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/build.gradle.kts
@@ -0,0 +1,25 @@
+plugins {
+    id("java")
+}
+
+group = "project"
+version = "1.0-SNAPSHOT"
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    testImplementation(platform("org.junit:junit-bom:5.10.0"))
+    testImplementation("org.junit.jupiter:junit-jupiter")
+
+    // JUnit 4
+    testImplementation("junit:junit:4.13.2")
+
+    // Hamcrest
+    testImplementation("org.hamcrest:hamcrest:2.2")
+}
+
+tasks.test {
+    useJUnit()
+}
diff --git a/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/Attributes.class b/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/Attributes.class
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diff --git a/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/Document.class b/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/Document.class
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diff --git a/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/DocumentManagementSystem.class b/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/DocumentManagementSystem.class
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diff --git a/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/ImageImporter.class b/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/ImageImporter.class
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diff --git a/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/Importer.class b/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/Importer.class
new file mode 100644
index 0000000..fb652be
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diff --git a/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/InvoiceImporter.class b/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/InvoiceImporter.class
new file mode 100644
index 0000000..599370b
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diff --git a/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/LetterImporter.class b/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/LetterImporter.class
new file mode 100644
index 0000000..7768cd9
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diff --git a/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/Query.class b/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/Query.class
new file mode 100644
index 0000000..85658c8
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diff --git a/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/ReportImporter.class b/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/ReportImporter.class
new file mode 100644
index 0000000..d91d6dc
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diff --git a/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/TextFile.class b/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/TextFile.class
new file mode 100644
index 0000000..1df9542
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diff --git a/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/UnknownFileTypeException.class b/book/real-world-software-development/chapter4/document-management/build/classes/java/main/project/UnknownFileTypeException.class
new file mode 100644
index 0000000..e58bfe5
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diff --git a/book/real-world-software-development/chapter4/document-management/build/classes/java/test/chpater4/DocumentManagementSystemTest.class b/book/real-world-software-development/chapter4/document-management/build/classes/java/test/chpater4/DocumentManagementSystemTest.class
new file mode 100644
index 0000000..ae8f03d
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diff --git a/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/classes/chpater4.DocumentManagementSystemTest.html b/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/classes/chpater4.DocumentManagementSystemTest.html
new file mode 100644
index 0000000..63acf32
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/classes/chpater4.DocumentManagementSystemTest.html
@@ -0,0 +1,484 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
+<meta http-equiv="x-ua-compatible" content="IE=edge"/>
+<title>Test results - Class chpater4.DocumentManagementSystemTest</title>
+<link href="../css/base-style.css" rel="stylesheet" type="text/css"/>
+<link href="../css/style.css" rel="stylesheet" type="text/css"/>
+<script src="../js/report.js" type="text/javascript"></script>
+</head>
+<body>
+<div id="content">
+<h1>Class chpater4.DocumentManagementSystemTest</h1>
+<div class="breadcrumbs">
+<a href="../index.html">all</a> &gt; 
+<a href="../packages/chpater4.html">chpater4</a> &gt; DocumentManagementSystemTest</div>
+<div id="summary">
+<table>
+<tr>
+<td>
+<div class="summaryGroup">
+<table>
+<tr>
+<td>
+<div class="infoBox" id="tests">
+<div class="counter">8</div>
+<p>tests</p>
+</div>
+</td>
+<td>
+<div class="infoBox" id="failures">
+<div class="counter">7</div>
+<p>failures</p>
+</div>
+</td>
+<td>
+<div class="infoBox" id="ignored">
+<div class="counter">0</div>
+<p>ignored</p>
+</div>
+</td>
+<td>
+<div class="infoBox" id="duration">
+<div class="counter">0.011s</div>
+<p>duration</p>
+</div>
+</td>
+</tr>
+</table>
+</div>
+</td>
+<td>
+<div class="infoBox failures" id="successRate">
+<div class="percent">12%</div>
+<p>successful</p>
+</div>
+</td>
+</tr>
+</table>
+</div>
+<div id="tabs">
+<ul class="tabLinks">
+<li>
+<a href="#tab0">Failed tests</a>
+</li>
+<li>
+<a href="#tab1">Tests</a>
+</li>
+</ul>
+<div id="tab0" class="tab">
+<h2>Failed tests</h2>
+<div class="test">
+<a name="shouldBeAbleToSearchFilesByAttributes"></a>
+<h3 class="failures">shouldBeAbleToSearchFilesByAttributes</h3>
+<span class="code">
+<pre>java.io.FileNotFoundException: src/test/resources/patient.letter
+	at project.DocumentManagementSystem.importFile(DocumentManagementSystem.java:30)
+	at chpater4.DocumentManagementSystemTest.shouldBeAbleToSearchFilesByAttributes(DocumentManagementSystemTest.java:103)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
+	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
+	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
+	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
+	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
+	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
+	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
+	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
+	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
+	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:112)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:40)
+	at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:60)
+	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:52)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
+	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
+	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
+	at jdk.proxy1/jdk.proxy1.$Proxy2.processTestClass(Unknown Source)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
+	at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:113)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:65)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
+</pre>
+</span>
+</div>
+<div class="test">
+<a name="shouldImportFile"></a>
+<h3 class="failures">shouldImportFile</h3>
+<span class="code">
+<pre>java.io.FileNotFoundException: src/test/resources/patient.letter
+	at project.DocumentManagementSystem.importFile(DocumentManagementSystem.java:30)
+	at chpater4.DocumentManagementSystemTest.shouldImportFile(DocumentManagementSystemTest.java:37)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
+	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
+	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
+	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
+	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
+	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
+	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
+	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
+	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
+	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:112)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:40)
+	at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:60)
+	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:52)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
+	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
+	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
+	at jdk.proxy1/jdk.proxy1.$Proxy2.processTestClass(Unknown Source)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
+	at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:113)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:65)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
+</pre>
+</span>
+</div>
+<div class="test">
+<a name="shouldImportImageAttributes"></a>
+<h3 class="failures">shouldImportImageAttributes</h3>
+<span class="code">
+<pre>java.io.FileNotFoundException: src/test/resources/xray.jpg
+	at project.DocumentManagementSystem.importFile(DocumentManagementSystem.java:30)
+	at chpater4.DocumentManagementSystemTest.shouldImportImageAttributes(DocumentManagementSystemTest.java:78)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
+	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
+	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
+	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
+	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
+	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
+	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
+	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
+	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
+	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:112)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:40)
+	at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:60)
+	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:52)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
+	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
+	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
+	at jdk.proxy1/jdk.proxy1.$Proxy2.processTestClass(Unknown Source)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
+	at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:113)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:65)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
+</pre>
+</span>
+</div>
+<div class="test">
+<a name="shouldImportInvoiceAttributes"></a>
+<h3 class="failures">shouldImportInvoiceAttributes</h3>
+<span class="code">
+<pre>java.io.FileNotFoundException: src/test/resources/patient.invoice
+	at project.DocumentManagementSystem.importFile(DocumentManagementSystem.java:30)
+	at chpater4.DocumentManagementSystemTest.shouldImportInvoiceAttributes(DocumentManagementSystemTest.java:91)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
+	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
+	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
+	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
+	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
+	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
+	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
+	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
+	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
+	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:112)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:40)
+	at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:60)
+	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:52)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
+	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
+	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
+	at jdk.proxy1/jdk.proxy1.$Proxy2.processTestClass(Unknown Source)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
+	at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:113)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:65)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
+</pre>
+</span>
+</div>
+<div class="test">
+<a name="shouldImportLetterAttributes"></a>
+<h3 class="failures">shouldImportLetterAttributes</h3>
+<span class="code">
+<pre>java.io.FileNotFoundException: src/test/resources/patient.letter
+	at project.DocumentManagementSystem.importFile(DocumentManagementSystem.java:30)
+	at chpater4.DocumentManagementSystemTest.shouldImportLetterAttributes(DocumentManagementSystemTest.java:49)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
+	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
+	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
+	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
+	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
+	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
+	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
+	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
+	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
+	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:112)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:40)
+	at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:60)
+	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:52)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
+	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
+	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
+	at jdk.proxy1/jdk.proxy1.$Proxy2.processTestClass(Unknown Source)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
+	at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:113)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:65)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
+</pre>
+</span>
+</div>
+<div class="test">
+<a name="shouldImportReportAttributes"></a>
+<h3 class="failures">shouldImportReportAttributes</h3>
+<span class="code">
+<pre>java.io.FileNotFoundException: src/test/resources/patient.report
+	at project.DocumentManagementSystem.importFile(DocumentManagementSystem.java:30)
+	at chpater4.DocumentManagementSystemTest.shouldImportReportAttributes(DocumentManagementSystemTest.java:69)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
+	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
+	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
+	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
+	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
+	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
+	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
+	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
+	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
+	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:112)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:40)
+	at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:60)
+	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:52)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
+	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
+	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
+	at jdk.proxy1/jdk.proxy1.$Proxy2.processTestClass(Unknown Source)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
+	at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:113)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:65)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
+</pre>
+</span>
+</div>
+<div class="test">
+<a name="shouldNotImportUnknownFile"></a>
+<h3 class="failures">shouldNotImportUnknownFile</h3>
+<span class="code">
+<pre>java.lang.Exception: Unexpected exception, expected&lt;project.UnknownFileTypeException&gt; but was&lt;java.io.FileNotFoundException&gt;
+	at org.junit.internal.runners.statements.ExpectException.evaluate(ExpectException.java:30)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
+	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
+	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
+	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
+	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
+	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
+	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:112)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:40)
+	at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:60)
+	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:52)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
+	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
+	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
+	at jdk.proxy1/jdk.proxy1.$Proxy2.processTestClass(Unknown Source)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
+	at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:113)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:65)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
+Caused by: java.io.FileNotFoundException: src/test/resources/unknown.txt
+	at project.DocumentManagementSystem.importFile(DocumentManagementSystem.java:30)
+	at chpater4.DocumentManagementSystemTest.shouldNotImportUnknownFile(DocumentManagementSystemTest.java:123)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
+	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
+	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
+	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
+	at org.junit.internal.runners.statements.ExpectException.evaluate(ExpectException.java:19)
+	... 33 more
+</pre>
+</span>
+</div>
+</div>
+<div id="tab1" class="tab">
+<h2>Tests</h2>
+<table>
+<thead>
+<tr>
+<th>Test</th>
+<th>Duration</th>
+<th>Result</th>
+</tr>
+</thead>
+<tr>
+<td class="failures">shouldBeAbleToSearchFilesByAttributes</td>
+<td class="failures">0.001s</td>
+<td class="failures">failed</td>
+</tr>
+<tr>
+<td class="failures">shouldImportFile</td>
+<td class="failures">0.001s</td>
+<td class="failures">failed</td>
+</tr>
+<tr>
+<td class="failures">shouldImportImageAttributes</td>
+<td class="failures">0.001s</td>
+<td class="failures">failed</td>
+</tr>
+<tr>
+<td class="failures">shouldImportInvoiceAttributes</td>
+<td class="failures">0s</td>
+<td class="failures">failed</td>
+</tr>
+<tr>
+<td class="failures">shouldImportLetterAttributes</td>
+<td class="failures">0s</td>
+<td class="failures">failed</td>
+</tr>
+<tr>
+<td class="failures">shouldImportReportAttributes</td>
+<td class="failures">0.008s</td>
+<td class="failures">failed</td>
+</tr>
+<tr>
+<td class="success">shouldNotImportMissingFile</td>
+<td class="success">0s</td>
+<td class="success">passed</td>
+</tr>
+<tr>
+<td class="failures">shouldNotImportUnknownFile</td>
+<td class="failures">0s</td>
+<td class="failures">failed</td>
+</tr>
+</table>
+</div>
+</div>
+<div id="footer">
+<p>
+<div>
+<label class="hidden" id="label-for-line-wrapping-toggle" for="line-wrapping-toggle">Wrap lines
+<input id="line-wrapping-toggle" type="checkbox" autocomplete="off"/>
+</label>
+</div>Generated by 
+<a href="http://www.gradle.org">Gradle 8.5</a> at 2025. 5. 17. 오후 12:03:38</p>
+</div>
+</div>
+</body>
+</html>
diff --git a/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/css/base-style.css b/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/css/base-style.css
new file mode 100644
index 0000000..4afa73e
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/css/base-style.css
@@ -0,0 +1,179 @@
+
+body {
+    margin: 0;
+    padding: 0;
+    font-family: sans-serif;
+    font-size: 12pt;
+}
+
+body, a, a:visited {
+    color: #303030;
+}
+
+#content {
+    padding-left: 50px;
+    padding-right: 50px;
+    padding-top: 30px;
+    padding-bottom: 30px;
+}
+
+#content h1 {
+    font-size: 160%;
+    margin-bottom: 10px;
+}
+
+#footer {
+    margin-top: 100px;
+    font-size: 80%;
+    white-space: nowrap;
+}
+
+#footer, #footer a {
+    color: #a0a0a0;
+}
+
+#line-wrapping-toggle {
+    vertical-align: middle;
+}
+
+#label-for-line-wrapping-toggle {
+    vertical-align: middle;
+}
+
+ul {
+    margin-left: 0;
+}
+
+h1, h2, h3 {
+    white-space: nowrap;
+}
+
+h2 {
+    font-size: 120%;
+}
+
+ul.tabLinks {
+    padding-left: 0;
+    padding-top: 10px;
+    padding-bottom: 10px;
+    overflow: auto;
+    min-width: 800px;
+    width: auto !important;
+    width: 800px;
+}
+
+ul.tabLinks li {
+    float: left;
+    height: 100%;
+    list-style: none;
+    padding-left: 10px;
+    padding-right: 10px;
+    padding-top: 5px;
+    padding-bottom: 5px;
+    margin-bottom: 0;
+    -moz-border-radius: 7px;
+    border-radius: 7px;
+    margin-right: 25px;
+    border: solid 1px #d4d4d4;
+    background-color: #f0f0f0;
+}
+
+ul.tabLinks li:hover {
+    background-color: #fafafa;
+}
+
+ul.tabLinks li.selected {
+    background-color: #c5f0f5;
+    border-color: #c5f0f5;
+}
+
+ul.tabLinks a {
+    font-size: 120%;
+    display: block;
+    outline: none;
+    text-decoration: none;
+    margin: 0;
+    padding: 0;
+}
+
+ul.tabLinks li h2 {
+    margin: 0;
+    padding: 0;
+}
+
+div.tab {
+}
+
+div.selected {
+    display: block;
+}
+
+div.deselected {
+    display: none;
+}
+
+div.tab table {
+    min-width: 350px;
+    width: auto !important;
+    width: 350px;
+    border-collapse: collapse;
+}
+
+div.tab th, div.tab table {
+    border-bottom: solid #d0d0d0 1px;
+}
+
+div.tab th {
+    text-align: left;
+    white-space: nowrap;
+    padding-left: 6em;
+}
+
+div.tab th:first-child {
+    padding-left: 0;
+}
+
+div.tab td {
+    white-space: nowrap;
+    padding-left: 6em;
+    padding-top: 5px;
+    padding-bottom: 5px;
+}
+
+div.tab td:first-child {
+    padding-left: 0;
+}
+
+div.tab td.numeric, div.tab th.numeric {
+    text-align: right;
+}
+
+span.code {
+    display: inline-block;
+    margin-top: 0em;
+    margin-bottom: 1em;
+}
+
+span.code pre {
+    font-size: 11pt;
+    padding-top: 10px;
+    padding-bottom: 10px;
+    padding-left: 10px;
+    padding-right: 10px;
+    margin: 0;
+    background-color: #f7f7f7;
+    border: solid 1px #d0d0d0;
+    min-width: 700px;
+    width: auto !important;
+    width: 700px;
+}
+
+span.wrapped pre {
+    word-wrap: break-word;
+    white-space: pre-wrap;
+    word-break: break-all;
+}
+
+label.hidden {
+    display: none;
+}
\ No newline at end of file
diff --git a/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/css/style.css b/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/css/style.css
new file mode 100644
index 0000000..3dc4913
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/css/style.css
@@ -0,0 +1,84 @@
+
+#summary {
+    margin-top: 30px;
+    margin-bottom: 40px;
+}
+
+#summary table {
+    border-collapse: collapse;
+}
+
+#summary td {
+    vertical-align: top;
+}
+
+.breadcrumbs, .breadcrumbs a {
+    color: #606060;
+}
+
+.infoBox {
+    width: 110px;
+    padding-top: 15px;
+    padding-bottom: 15px;
+    text-align: center;
+}
+
+.infoBox p {
+    margin: 0;
+}
+
+.counter, .percent {
+    font-size: 120%;
+    font-weight: bold;
+    margin-bottom: 8px;
+}
+
+#duration {
+    width: 125px;
+}
+
+#successRate, .summaryGroup {
+    border: solid 2px #d0d0d0;
+    -moz-border-radius: 10px;
+    border-radius: 10px;
+}
+
+#successRate {
+    width: 140px;
+    margin-left: 35px;
+}
+
+#successRate .percent {
+    font-size: 180%;
+}
+
+.success, .success a {
+    color: #008000;
+}
+
+div.success, #successRate.success {
+    background-color: #bbd9bb;
+    border-color: #008000;
+}
+
+.failures, .failures a {
+    color: #b60808;
+}
+
+.skipped, .skipped a {
+    color: #c09853;
+}
+
+div.failures, #successRate.failures {
+    background-color: #ecdada;
+    border-color: #b60808;
+}
+
+ul.linkList {
+    padding-left: 0;
+}
+
+ul.linkList li {
+    list-style: none;
+    margin-bottom: 5px;
+}
diff --git a/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/index.html b/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/index.html
new file mode 100644
index 0000000..9444ce2
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/index.html
@@ -0,0 +1,169 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
+<meta http-equiv="x-ua-compatible" content="IE=edge"/>
+<title>Test results - Test Summary</title>
+<link href="css/base-style.css" rel="stylesheet" type="text/css"/>
+<link href="css/style.css" rel="stylesheet" type="text/css"/>
+<script src="js/report.js" type="text/javascript"></script>
+</head>
+<body>
+<div id="content">
+<h1>Test Summary</h1>
+<div id="summary">
+<table>
+<tr>
+<td>
+<div class="summaryGroup">
+<table>
+<tr>
+<td>
+<div class="infoBox" id="tests">
+<div class="counter">8</div>
+<p>tests</p>
+</div>
+</td>
+<td>
+<div class="infoBox" id="failures">
+<div class="counter">7</div>
+<p>failures</p>
+</div>
+</td>
+<td>
+<div class="infoBox" id="ignored">
+<div class="counter">0</div>
+<p>ignored</p>
+</div>
+</td>
+<td>
+<div class="infoBox" id="duration">
+<div class="counter">0.011s</div>
+<p>duration</p>
+</div>
+</td>
+</tr>
+</table>
+</div>
+</td>
+<td>
+<div class="infoBox failures" id="successRate">
+<div class="percent">12%</div>
+<p>successful</p>
+</div>
+</td>
+</tr>
+</table>
+</div>
+<div id="tabs">
+<ul class="tabLinks">
+<li>
+<a href="#tab0">Failed tests</a>
+</li>
+<li>
+<a href="#tab1">Packages</a>
+</li>
+<li>
+<a href="#tab2">Classes</a>
+</li>
+</ul>
+<div id="tab0" class="tab">
+<h2>Failed tests</h2>
+<ul class="linkList">
+<li>
+<a href="classes/chpater4.DocumentManagementSystemTest.html">DocumentManagementSystemTest</a>.
+<a href="classes/chpater4.DocumentManagementSystemTest.html#shouldBeAbleToSearchFilesByAttributes">shouldBeAbleToSearchFilesByAttributes</a>
+</li>
+<li>
+<a href="classes/chpater4.DocumentManagementSystemTest.html">DocumentManagementSystemTest</a>.
+<a href="classes/chpater4.DocumentManagementSystemTest.html#shouldImportFile">shouldImportFile</a>
+</li>
+<li>
+<a href="classes/chpater4.DocumentManagementSystemTest.html">DocumentManagementSystemTest</a>.
+<a href="classes/chpater4.DocumentManagementSystemTest.html#shouldImportImageAttributes">shouldImportImageAttributes</a>
+</li>
+<li>
+<a href="classes/chpater4.DocumentManagementSystemTest.html">DocumentManagementSystemTest</a>.
+<a href="classes/chpater4.DocumentManagementSystemTest.html#shouldImportInvoiceAttributes">shouldImportInvoiceAttributes</a>
+</li>
+<li>
+<a href="classes/chpater4.DocumentManagementSystemTest.html">DocumentManagementSystemTest</a>.
+<a href="classes/chpater4.DocumentManagementSystemTest.html#shouldImportLetterAttributes">shouldImportLetterAttributes</a>
+</li>
+<li>
+<a href="classes/chpater4.DocumentManagementSystemTest.html">DocumentManagementSystemTest</a>.
+<a href="classes/chpater4.DocumentManagementSystemTest.html#shouldImportReportAttributes">shouldImportReportAttributes</a>
+</li>
+<li>
+<a href="classes/chpater4.DocumentManagementSystemTest.html">DocumentManagementSystemTest</a>.
+<a href="classes/chpater4.DocumentManagementSystemTest.html#shouldNotImportUnknownFile">shouldNotImportUnknownFile</a>
+</li>
+</ul>
+</div>
+<div id="tab1" class="tab">
+<h2>Packages</h2>
+<table>
+<thead>
+<tr>
+<th>Package</th>
+<th>Tests</th>
+<th>Failures</th>
+<th>Ignored</th>
+<th>Duration</th>
+<th>Success rate</th>
+</tr>
+</thead>
+<tbody>
+<tr>
+<td class="failures">
+<a href="packages/chpater4.html">chpater4</a>
+</td>
+<td>8</td>
+<td>7</td>
+<td>0</td>
+<td>0.011s</td>
+<td class="failures">12%</td>
+</tr>
+</tbody>
+</table>
+</div>
+<div id="tab2" class="tab">
+<h2>Classes</h2>
+<table>
+<thead>
+<tr>
+<th>Class</th>
+<th>Tests</th>
+<th>Failures</th>
+<th>Ignored</th>
+<th>Duration</th>
+<th>Success rate</th>
+</tr>
+</thead>
+<tbody>
+<tr>
+<td class="failures">
+<a href="classes/chpater4.DocumentManagementSystemTest.html">chpater4.DocumentManagementSystemTest</a>
+</td>
+<td>8</td>
+<td>7</td>
+<td>0</td>
+<td>0.011s</td>
+<td class="failures">12%</td>
+</tr>
+</tbody>
+</table>
+</div>
+</div>
+<div id="footer">
+<p>
+<div>
+<label class="hidden" id="label-for-line-wrapping-toggle" for="line-wrapping-toggle">Wrap lines
+<input id="line-wrapping-toggle" type="checkbox" autocomplete="off"/>
+</label>
+</div>Generated by 
+<a href="http://www.gradle.org">Gradle 8.5</a> at 2025. 5. 17. 오후 12:03:38</p>
+</div>
+</div>
+</body>
+</html>
diff --git a/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/js/report.js b/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/js/report.js
new file mode 100644
index 0000000..83bab4a
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/js/report.js
@@ -0,0 +1,194 @@
+(function (window, document) {
+    "use strict";
+
+    var tabs = {};
+
+    function changeElementClass(element, classValue) {
+        if (element.getAttribute("className")) {
+            element.setAttribute("className", classValue);
+        } else {
+            element.setAttribute("class", classValue);
+        }
+    }
+
+    function getClassAttribute(element) {
+        if (element.getAttribute("className")) {
+            return element.getAttribute("className");
+        } else {
+            return element.getAttribute("class");
+        }
+    }
+
+    function addClass(element, classValue) {
+        changeElementClass(element, getClassAttribute(element) + " " + classValue);
+    }
+
+    function removeClass(element, classValue) {
+        changeElementClass(element, getClassAttribute(element).replace(classValue, ""));
+    }
+
+    function initTabs() {
+        var container = document.getElementById("tabs");
+
+        tabs.tabs = findTabs(container);
+        tabs.titles = findTitles(tabs.tabs);
+        tabs.headers = findHeaders(container);
+        tabs.select = select;
+        tabs.deselectAll = deselectAll;
+        tabs.select(0);
+
+        return true;
+    }
+
+    function getCheckBox() {
+        return document.getElementById("line-wrapping-toggle");
+    }
+
+    function getLabelForCheckBox() {
+        return document.getElementById("label-for-line-wrapping-toggle");
+    }
+
+    function findCodeBlocks() {
+        var spans = document.getElementById("tabs").getElementsByTagName("span");
+        var codeBlocks = [];
+        for (var i = 0; i < spans.length; ++i) {
+            if (spans[i].className.indexOf("code") >= 0) {
+                codeBlocks.push(spans[i]);
+            }
+        }
+        return codeBlocks;
+    }
+
+    function forAllCodeBlocks(operation) {
+        var codeBlocks = findCodeBlocks();
+
+        for (var i = 0; i < codeBlocks.length; ++i) {
+            operation(codeBlocks[i], "wrapped");
+        }
+    }
+
+    function toggleLineWrapping() {
+        var checkBox = getCheckBox();
+
+        if (checkBox.checked) {
+            forAllCodeBlocks(addClass);
+        } else {
+            forAllCodeBlocks(removeClass);
+        }
+    }
+
+    function initControls() {
+        if (findCodeBlocks().length > 0) {
+            var checkBox = getCheckBox();
+            var label = getLabelForCheckBox();
+
+            checkBox.onclick = toggleLineWrapping;
+            checkBox.checked = false;
+
+            removeClass(label, "hidden");
+         }
+    }
+
+    function switchTab() {
+        var id = this.id.substr(1);
+
+        for (var i = 0; i < tabs.tabs.length; i++) {
+            if (tabs.tabs[i].id === id) {
+                tabs.select(i);
+                break;
+            }
+        }
+
+        return false;
+    }
+
+    function select(i) {
+        this.deselectAll();
+
+        changeElementClass(this.tabs[i], "tab selected");
+        changeElementClass(this.headers[i], "selected");
+
+        while (this.headers[i].firstChild) {
+            this.headers[i].removeChild(this.headers[i].firstChild);
+        }
+
+        var h2 = document.createElement("H2");
+
+        h2.appendChild(document.createTextNode(this.titles[i]));
+        this.headers[i].appendChild(h2);
+    }
+
+    function deselectAll() {
+        for (var i = 0; i < this.tabs.length; i++) {
+            changeElementClass(this.tabs[i], "tab deselected");
+            changeElementClass(this.headers[i], "deselected");
+
+            while (this.headers[i].firstChild) {
+                this.headers[i].removeChild(this.headers[i].firstChild);
+            }
+
+            var a = document.createElement("A");
+
+            a.setAttribute("id", "ltab" + i);
+            a.setAttribute("href", "#tab" + i);
+            a.onclick = switchTab;
+            a.appendChild(document.createTextNode(this.titles[i]));
+
+            this.headers[i].appendChild(a);
+        }
+    }
+
+    function findTabs(container) {
+        return findChildElements(container, "DIV", "tab");
+    }
+
+    function findHeaders(container) {
+        var owner = findChildElements(container, "UL", "tabLinks");
+        return findChildElements(owner[0], "LI", null);
+    }
+
+    function findTitles(tabs) {
+        var titles = [];
+
+        for (var i = 0; i < tabs.length; i++) {
+            var tab = tabs[i];
+            var header = findChildElements(tab, "H2", null)[0];
+
+            header.parentNode.removeChild(header);
+
+            if (header.innerText) {
+                titles.push(header.innerText);
+            } else {
+                titles.push(header.textContent);
+            }
+        }
+
+        return titles;
+    }
+
+    function findChildElements(container, name, targetClass) {
+        var elements = [];
+        var children = container.childNodes;
+
+        for (var i = 0; i < children.length; i++) {
+            var child = children.item(i);
+
+            if (child.nodeType === 1 && child.nodeName === name) {
+                if (targetClass && child.className.indexOf(targetClass) < 0) {
+                    continue;
+                }
+
+                elements.push(child);
+            }
+        }
+
+        return elements;
+    }
+
+    // Entry point.
+
+    window.onload = function() {
+        initTabs();
+        initControls();
+    };
+} (window, window.document));
\ No newline at end of file
diff --git a/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/packages/chpater4.html b/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/packages/chpater4.html
new file mode 100644
index 0000000..9262d8b
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/build/reports/tests/test/packages/chpater4.html
@@ -0,0 +1,139 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
+<meta http-equiv="x-ua-compatible" content="IE=edge"/>
+<title>Test results - Package chpater4</title>
+<link href="../css/base-style.css" rel="stylesheet" type="text/css"/>
+<link href="../css/style.css" rel="stylesheet" type="text/css"/>
+<script src="../js/report.js" type="text/javascript"></script>
+</head>
+<body>
+<div id="content">
+<h1>Package chpater4</h1>
+<div class="breadcrumbs">
+<a href="../index.html">all</a> &gt; chpater4</div>
+<div id="summary">
+<table>
+<tr>
+<td>
+<div class="summaryGroup">
+<table>
+<tr>
+<td>
+<div class="infoBox" id="tests">
+<div class="counter">8</div>
+<p>tests</p>
+</div>
+</td>
+<td>
+<div class="infoBox" id="failures">
+<div class="counter">7</div>
+<p>failures</p>
+</div>
+</td>
+<td>
+<div class="infoBox" id="ignored">
+<div class="counter">0</div>
+<p>ignored</p>
+</div>
+</td>
+<td>
+<div class="infoBox" id="duration">
+<div class="counter">0.011s</div>
+<p>duration</p>
+</div>
+</td>
+</tr>
+</table>
+</div>
+</td>
+<td>
+<div class="infoBox failures" id="successRate">
+<div class="percent">12%</div>
+<p>successful</p>
+</div>
+</td>
+</tr>
+</table>
+</div>
+<div id="tabs">
+<ul class="tabLinks">
+<li>
+<a href="#tab0">Failed tests</a>
+</li>
+<li>
+<a href="#tab1">Classes</a>
+</li>
+</ul>
+<div id="tab0" class="tab">
+<h2>Failed tests</h2>
+<ul class="linkList">
+<li>
+<a href="../classes/chpater4.DocumentManagementSystemTest.html">DocumentManagementSystemTest</a>.
+<a href="../classes/chpater4.DocumentManagementSystemTest.html#shouldBeAbleToSearchFilesByAttributes">shouldBeAbleToSearchFilesByAttributes</a>
+</li>
+<li>
+<a href="../classes/chpater4.DocumentManagementSystemTest.html">DocumentManagementSystemTest</a>.
+<a href="../classes/chpater4.DocumentManagementSystemTest.html#shouldImportFile">shouldImportFile</a>
+</li>
+<li>
+<a href="../classes/chpater4.DocumentManagementSystemTest.html">DocumentManagementSystemTest</a>.
+<a href="../classes/chpater4.DocumentManagementSystemTest.html#shouldImportImageAttributes">shouldImportImageAttributes</a>
+</li>
+<li>
+<a href="../classes/chpater4.DocumentManagementSystemTest.html">DocumentManagementSystemTest</a>.
+<a href="../classes/chpater4.DocumentManagementSystemTest.html#shouldImportInvoiceAttributes">shouldImportInvoiceAttributes</a>
+</li>
+<li>
+<a href="../classes/chpater4.DocumentManagementSystemTest.html">DocumentManagementSystemTest</a>.
+<a href="../classes/chpater4.DocumentManagementSystemTest.html#shouldImportLetterAttributes">shouldImportLetterAttributes</a>
+</li>
+<li>
+<a href="../classes/chpater4.DocumentManagementSystemTest.html">DocumentManagementSystemTest</a>.
+<a href="../classes/chpater4.DocumentManagementSystemTest.html#shouldImportReportAttributes">shouldImportReportAttributes</a>
+</li>
+<li>
+<a href="../classes/chpater4.DocumentManagementSystemTest.html">DocumentManagementSystemTest</a>.
+<a href="../classes/chpater4.DocumentManagementSystemTest.html#shouldNotImportUnknownFile">shouldNotImportUnknownFile</a>
+</li>
+</ul>
+</div>
+<div id="tab1" class="tab">
+<h2>Classes</h2>
+<table>
+<thead>
+<tr>
+<th>Class</th>
+<th>Tests</th>
+<th>Failures</th>
+<th>Ignored</th>
+<th>Duration</th>
+<th>Success rate</th>
+</tr>
+</thead>
+<tr>
+<td class="failures">
+<a href="../classes/chpater4.DocumentManagementSystemTest.html">DocumentManagementSystemTest</a>
+</td>
+<td>8</td>
+<td>7</td>
+<td>0</td>
+<td>0.011s</td>
+<td class="failures">12%</td>
+</tr>
+</table>
+</div>
+</div>
+<div id="footer">
+<p>
+<div>
+<label class="hidden" id="label-for-line-wrapping-toggle" for="line-wrapping-toggle">Wrap lines
+<input id="line-wrapping-toggle" type="checkbox" autocomplete="off"/>
+</label>
+</div>Generated by 
+<a href="http://www.gradle.org">Gradle 8.5</a> at 2025. 5. 17. 오후 12:03:38</p>
+</div>
+</div>
+</body>
+</html>
diff --git a/book/real-world-software-development/chapter4/document-management/build/test-results/test/TEST-chpater4.DocumentManagementSystemTest.xml b/book/real-world-software-development/chapter4/document-management/build/test-results/test/TEST-chpater4.DocumentManagementSystemTest.xml
new file mode 100644
index 0000000..ce3a538
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/build/test-results/test/TEST-chpater4.DocumentManagementSystemTest.xml
@@ -0,0 +1,326 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<testsuite name="chpater4.DocumentManagementSystemTest" tests="8" skipped="0" failures="7" errors="0" timestamp="2025-05-17T03:03:38" hostname="Hyundooui-MacBookPro.local" time="0.011">
+  <properties/>
+  <testcase name="shouldImportReportAttributes" classname="chpater4.DocumentManagementSystemTest" time="0.008">
+    <failure message="java.io.FileNotFoundException: src/test/resources/patient.report" type="java.io.FileNotFoundException">java.io.FileNotFoundException: src/test/resources/patient.report
+	at project.DocumentManagementSystem.importFile(DocumentManagementSystem.java:30)
+	at chpater4.DocumentManagementSystemTest.shouldImportReportAttributes(DocumentManagementSystemTest.java:69)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
+	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
+	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
+	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
+	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
+	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
+	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
+	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
+	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
+	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:112)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:40)
+	at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:60)
+	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:52)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
+	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
+	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
+	at jdk.proxy1/jdk.proxy1.$Proxy2.processTestClass(Unknown Source)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
+	at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:113)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:65)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
+</failure>
+  </testcase>
+  <testcase name="shouldImportInvoiceAttributes" classname="chpater4.DocumentManagementSystemTest" time="0.0">
+    <failure message="java.io.FileNotFoundException: src/test/resources/patient.invoice" type="java.io.FileNotFoundException">java.io.FileNotFoundException: src/test/resources/patient.invoice
+	at project.DocumentManagementSystem.importFile(DocumentManagementSystem.java:30)
+	at chpater4.DocumentManagementSystemTest.shouldImportInvoiceAttributes(DocumentManagementSystemTest.java:91)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
+	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
+	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
+	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
+	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
+	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
+	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
+	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
+	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
+	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:112)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:40)
+	at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:60)
+	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:52)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
+	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
+	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
+	at jdk.proxy1/jdk.proxy1.$Proxy2.processTestClass(Unknown Source)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
+	at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:113)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:65)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
+</failure>
+  </testcase>
+  <testcase name="shouldBeAbleToSearchFilesByAttributes" classname="chpater4.DocumentManagementSystemTest" time="0.001">
+    <failure message="java.io.FileNotFoundException: src/test/resources/patient.letter" type="java.io.FileNotFoundException">java.io.FileNotFoundException: src/test/resources/patient.letter
+	at project.DocumentManagementSystem.importFile(DocumentManagementSystem.java:30)
+	at chpater4.DocumentManagementSystemTest.shouldBeAbleToSearchFilesByAttributes(DocumentManagementSystemTest.java:103)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
+	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
+	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
+	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
+	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
+	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
+	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
+	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
+	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
+	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:112)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:40)
+	at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:60)
+	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:52)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
+	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
+	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
+	at jdk.proxy1/jdk.proxy1.$Proxy2.processTestClass(Unknown Source)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
+	at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:113)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:65)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
+</failure>
+  </testcase>
+  <testcase name="shouldNotImportMissingFile" classname="chpater4.DocumentManagementSystemTest" time="0.0"/>
+  <testcase name="shouldNotImportUnknownFile" classname="chpater4.DocumentManagementSystemTest" time="0.0">
+    <failure message="java.lang.Exception: Unexpected exception, expected&lt;project.UnknownFileTypeException&gt; but was&lt;java.io.FileNotFoundException&gt;" type="java.lang.Exception">java.lang.Exception: Unexpected exception, expected&lt;project.UnknownFileTypeException&gt; but was&lt;java.io.FileNotFoundException&gt;
+	at org.junit.internal.runners.statements.ExpectException.evaluate(ExpectException.java:30)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
+	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
+	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
+	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
+	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
+	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
+	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:112)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:40)
+	at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:60)
+	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:52)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
+	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
+	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
+	at jdk.proxy1/jdk.proxy1.$Proxy2.processTestClass(Unknown Source)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
+	at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:113)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:65)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
+Caused by: java.io.FileNotFoundException: src/test/resources/unknown.txt
+	at project.DocumentManagementSystem.importFile(DocumentManagementSystem.java:30)
+	at chpater4.DocumentManagementSystemTest.shouldNotImportUnknownFile(DocumentManagementSystemTest.java:123)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
+	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
+	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
+	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
+	at org.junit.internal.runners.statements.ExpectException.evaluate(ExpectException.java:19)
+	... 33 more
+</failure>
+  </testcase>
+  <testcase name="shouldImportImageAttributes" classname="chpater4.DocumentManagementSystemTest" time="0.001">
+    <failure message="java.io.FileNotFoundException: src/test/resources/xray.jpg" type="java.io.FileNotFoundException">java.io.FileNotFoundException: src/test/resources/xray.jpg
+	at project.DocumentManagementSystem.importFile(DocumentManagementSystem.java:30)
+	at chpater4.DocumentManagementSystemTest.shouldImportImageAttributes(DocumentManagementSystemTest.java:78)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
+	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
+	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
+	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
+	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
+	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
+	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
+	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
+	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
+	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:112)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:40)
+	at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:60)
+	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:52)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
+	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
+	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
+	at jdk.proxy1/jdk.proxy1.$Proxy2.processTestClass(Unknown Source)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
+	at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:113)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:65)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
+</failure>
+  </testcase>
+  <testcase name="shouldImportLetterAttributes" classname="chpater4.DocumentManagementSystemTest" time="0.0">
+    <failure message="java.io.FileNotFoundException: src/test/resources/patient.letter" type="java.io.FileNotFoundException">java.io.FileNotFoundException: src/test/resources/patient.letter
+	at project.DocumentManagementSystem.importFile(DocumentManagementSystem.java:30)
+	at chpater4.DocumentManagementSystemTest.shouldImportLetterAttributes(DocumentManagementSystemTest.java:49)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
+	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
+	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
+	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
+	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
+	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
+	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
+	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
+	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
+	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:112)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:40)
+	at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:60)
+	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:52)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
+	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
+	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
+	at jdk.proxy1/jdk.proxy1.$Proxy2.processTestClass(Unknown Source)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
+	at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:113)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:65)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
+</failure>
+  </testcase>
+  <testcase name="shouldImportFile" classname="chpater4.DocumentManagementSystemTest" time="0.001">
+    <failure message="java.io.FileNotFoundException: src/test/resources/patient.letter" type="java.io.FileNotFoundException">java.io.FileNotFoundException: src/test/resources/patient.letter
+	at project.DocumentManagementSystem.importFile(DocumentManagementSystem.java:30)
+	at chpater4.DocumentManagementSystemTest.shouldImportFile(DocumentManagementSystemTest.java:37)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
+	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
+	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
+	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
+	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
+	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
+	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
+	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
+	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
+	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
+	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
+	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
+	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:112)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
+	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:40)
+	at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:60)
+	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:52)
+	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
+	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
+	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
+	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
+	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
+	at jdk.proxy1/jdk.proxy1.$Proxy2.processTestClass(Unknown Source)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
+	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
+	at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:113)
+	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:65)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
+	at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
+</failure>
+  </testcase>
+  <system-out><![CDATA[]]></system-out>
+  <system-err><![CDATA[]]></system-err>
+</testsuite>
diff --git a/book/real-world-software-development/chapter4/document-management/build/test-results/test/binary/output.bin b/book/real-world-software-development/chapter4/document-management/build/test-results/test/binary/output.bin
new file mode 100644
index 0000000..e69de29
diff --git a/book/real-world-software-development/chapter4/document-management/build/test-results/test/binary/output.bin.idx b/book/real-world-software-development/chapter4/document-management/build/test-results/test/binary/output.bin.idx
new file mode 100644
index 0000000..f76dd23
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new file mode 100644
index 0000000..3e733cf
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diff --git a/book/real-world-software-development/chapter4/document-management/build/tmp/compileJava/compileTransaction/stash-dir/DocumentManagementSystem.class.uniqueId0 b/book/real-world-software-development/chapter4/document-management/build/tmp/compileJava/compileTransaction/stash-dir/DocumentManagementSystem.class.uniqueId0
new file mode 100644
index 0000000..33b34e1
Binary files /dev/null and b/book/real-world-software-development/chapter4/document-management/build/tmp/compileJava/compileTransaction/stash-dir/DocumentManagementSystem.class.uniqueId0 differ
diff --git a/book/real-world-software-development/chapter4/document-management/build/tmp/compileJava/previous-compilation-data.bin b/book/real-world-software-development/chapter4/document-management/build/tmp/compileJava/previous-compilation-data.bin
new file mode 100644
index 0000000..de02644
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diff --git a/book/real-world-software-development/chapter4/document-management/build/tmp/compileTestJava/previous-compilation-data.bin b/book/real-world-software-development/chapter4/document-management/build/tmp/compileTestJava/previous-compilation-data.bin
new file mode 100644
index 0000000..1e592a3
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diff --git a/book/real-world-software-development/chapter4/document-management/gradle/wrapper/gradle-wrapper.jar b/book/real-world-software-development/chapter4/document-management/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 0000000..249e583
Binary files /dev/null and b/book/real-world-software-development/chapter4/document-management/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/book/real-world-software-development/chapter4/document-management/gradle/wrapper/gradle-wrapper.properties b/book/real-world-software-development/chapter4/document-management/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 0000000..398684e
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,6 @@
+#Sat May 17 10:03:06 KST 2025
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.5-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
diff --git a/book/real-world-software-development/chapter4/document-management/gradlew b/book/real-world-software-development/chapter4/document-management/gradlew
new file mode 100755
index 0000000..1b6c787
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/gradlew
@@ -0,0 +1,234 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
+
+APP_NAME="Gradle"
+APP_BASE_NAME=${0##*/}
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"
diff --git a/book/real-world-software-development/chapter4/document-management/gradlew.bat b/book/real-world-software-development/chapter4/document-management/gradlew.bat
new file mode 100644
index 0000000..107acd3
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/gradlew.bat
@@ -0,0 +1,89 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/book/real-world-software-development/chapter4/document-management/settings.gradle.kts b/book/real-world-software-development/chapter4/document-management/settings.gradle.kts
new file mode 100644
index 0000000..c44848c
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/settings.gradle.kts
@@ -0,0 +1,2 @@
+rootProject.name = "document-management"
+
diff --git a/book/real-world-software-development/chapter4/document-management/src/main/java/project/Attributes.java b/book/real-world-software-development/chapter4/document-management/src/main/java/project/Attributes.java
new file mode 100644
index 0000000..6550fcb
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/src/main/java/project/Attributes.java
@@ -0,0 +1,14 @@
+package project;
+
+
+public final class Attributes
+{
+    public static final String PATH = "path";
+    public static final String PATIENT = "patient";
+    public static final String ADDRESS = "address";
+    public static final String BODY = "body";
+    public static final String WIDTH = "width";
+    public static final String HEIGHT = "height";
+    public static final String TYPE = "type";
+    public static final String AMOUNT = "amount";
+}
\ No newline at end of file
diff --git a/book/real-world-software-development/chapter4/document-management/src/main/java/project/Document.java b/book/real-world-software-development/chapter4/document-management/src/main/java/project/Document.java
new file mode 100644
index 0000000..80fb75f
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/src/main/java/project/Document.java
@@ -0,0 +1,16 @@
+package project;
+
+import java.util.Map;
+
+public class Document {
+    private final Map<String, String> attributes;
+
+    Document(Map<String, String> attributes) {
+        this.attributes = attributes;
+    }
+
+    public String getAttribute(final String attributeName) {
+        return attributes.get(attributeName);
+    }
+
+}
diff --git a/book/real-world-software-development/chapter4/document-management/src/main/java/project/DocumentManagementSystem.java b/book/real-world-software-development/chapter4/document-management/src/main/java/project/DocumentManagementSystem.java
new file mode 100644
index 0000000..eae7723
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/src/main/java/project/DocumentManagementSystem.java
@@ -0,0 +1,60 @@
+package project;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.util.*;
+import java.util.stream.Collectors;
+
+import static java.util.Collections.unmodifiableList;
+
+public class DocumentManagementSystem {
+    private final List<Document> documents = new ArrayList<>();
+    private final List<Document> documentsView = unmodifiableList(documents);
+
+    private final Map<String, Importer> extensionToImporter = new HashMap<>();
+
+    public DocumentManagementSystem() {
+        extensionToImporter.put("letter", new LetterImporter());
+        extensionToImporter.put("report", new ReportImporter());
+        extensionToImporter.put("jpg", new ImageImporter());
+    }
+
+    {
+        extensionToImporter.put("invoice", new InvoiceImporter());
+    }
+
+    public void importFile(final String path) throws IOException {
+        final File file = new File(path);
+        if (!file.exists()) {
+            throw new FileNotFoundException(path);
+        }
+
+        final int separatorIndex = path.lastIndexOf('.');
+        if (separatorIndex != -1) {
+            if (separatorIndex == path.length()) {
+                throw new UnknownFileTypeException("No extension found For file: " + path);
+            }
+            final String extension = path.substring(separatorIndex + 1);
+            final Importer importer = extensionToImporter.get(extension);
+            if (importer == null) {
+                throw new UnknownFileTypeException("For file: " + path);
+            }
+
+            final Document document = importer.importFile(file);
+            documents.add(document);
+        } else {
+            throw new UnknownFileTypeException("No extension found For file: " + path);
+        }
+    }
+
+    public List<Document> contents() {
+        return documentsView;
+    }
+
+    public List<Document> search(final String query) {
+        return documents.stream()
+                .filter(Query.parse(query))
+                .collect(Collectors.toList());
+    }
+}
\ No newline at end of file
diff --git a/book/real-world-software-development/chapter4/document-management/src/main/java/project/ImageImporter.java b/book/real-world-software-development/chapter4/document-management/src/main/java/project/ImageImporter.java
new file mode 100644
index 0000000..85c14a9
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/src/main/java/project/ImageImporter.java
@@ -0,0 +1,25 @@
+package project;
+
+import javax.imageio.ImageIO;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+import static project.Attributes.*;
+
+public class ImageImporter implements Importer{
+
+    @Override
+    public Document importFile(File file) throws IOException {
+        final Map<String, String> attributes = new HashMap<>();
+        attributes.put(PATH, file.getPath());
+
+        final BufferedImage image = ImageIO.read(file);
+        attributes.put(WIDTH, String.valueOf(image.getWidth()));
+        attributes.put(HEIGHT, String.valueOf(image.getHeight()));
+        attributes.put(TYPE, "IMAGE");
+        return new Document(attributes);
+    }
+
+}
diff --git a/book/real-world-software-development/chapter4/document-management/src/main/java/project/Importer.java b/book/real-world-software-development/chapter4/document-management/src/main/java/project/Importer.java
new file mode 100644
index 0000000..3610795
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/src/main/java/project/Importer.java
@@ -0,0 +1,8 @@
+package project;
+
+import java.io.File;
+import java.io.IOException;
+
+public interface Importer {
+    Document importFile(File file) throws IOException;
+}
diff --git a/book/real-world-software-development/chapter4/document-management/src/main/java/project/InvoiceImporter.java b/book/real-world-software-development/chapter4/document-management/src/main/java/project/InvoiceImporter.java
new file mode 100644
index 0000000..9991ac8
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/src/main/java/project/InvoiceImporter.java
@@ -0,0 +1,27 @@
+package project;
+
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Map;
+
+import static project.Attributes.*;
+
+class InvoiceImporter implements Importer {
+    private static final String NAME_PREFIX = "Dear ";
+    private static final String AMOUNT_PREFIX = "Amount: ";
+
+    // tag::importFile[]
+    @Override
+    public Document importFile(final File file) throws IOException {
+        final TextFile textFile = new TextFile(file);
+
+        textFile.addLineSuffix(NAME_PREFIX, PATIENT);
+        textFile.addLineSuffix(AMOUNT_PREFIX, AMOUNT);
+
+        final Map<String, String> attributes = textFile.getAttributes();
+        attributes.put(TYPE, "INVOICE");
+        return new Document(attributes);
+    }
+    // end::importFile[]
+}
diff --git a/book/real-world-software-development/chapter4/document-management/src/main/java/project/LetterImporter.java b/book/real-world-software-development/chapter4/document-management/src/main/java/project/LetterImporter.java
new file mode 100644
index 0000000..4d96a0e
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/src/main/java/project/LetterImporter.java
@@ -0,0 +1,26 @@
+package project;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Map;
+
+import static project.Attributes.*;
+
+
+class LetterImporter implements Importer {
+    private static final String NAME_PREFIX = "Dear ";
+
+    @Override
+    public Document importFile(final File file) throws IOException {
+        final TextFile textFile = new TextFile(file);
+
+        textFile.addLineSuffix(NAME_PREFIX, PATIENT);
+
+        final int lineNumber = textFile.addLines(2, String::isEmpty, ADDRESS);
+        textFile.addLines(lineNumber + 1, (line) -> line.startsWith("regards,"), BODY);
+
+        final Map<String, String> attributes = textFile.getAttributes();
+        attributes.put(TYPE, "LETTER");
+        return new Document(attributes);
+    }
+}
diff --git a/book/real-world-software-development/chapter4/document-management/src/main/java/project/Query.java b/book/real-world-software-development/chapter4/document-management/src/main/java/project/Query.java
new file mode 100644
index 0000000..5dd6301
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/src/main/java/project/Query.java
@@ -0,0 +1,32 @@
+package project;
+
+import java.util.Arrays;
+import java.util.Map;
+import java.util.function.Predicate;
+
+import static java.util.stream.Collectors.toMap;
+
+class Query implements Predicate<Document> {
+    private final Map<String, String> clauses;
+
+    static Query parse(final String query) {
+        return new Query(Arrays.stream(query.split(","))
+                .map(str -> str.split(":"))
+                .collect(toMap(x -> x[0], x -> x[1])));
+    }
+
+    private Query(final Map<String, String> clauses) {
+        this.clauses = clauses;
+    }
+
+    @Override
+    public boolean test(final Document document) {
+        return clauses.entrySet()
+                .stream()
+                .allMatch(entry -> {
+                    final String documentValue = document.getAttribute(entry.getKey());
+                    final String queryValue = entry.getValue();
+                    return documentValue != null && documentValue.contains(queryValue);
+                });
+    }
+}
diff --git a/book/real-world-software-development/chapter4/document-management/src/main/java/project/ReportImporter.java b/book/real-world-software-development/chapter4/document-management/src/main/java/project/ReportImporter.java
new file mode 100644
index 0000000..520a9fe
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/src/main/java/project/ReportImporter.java
@@ -0,0 +1,23 @@
+package project;
+
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Map;
+import static project.Attributes.*;
+
+
+class ReportImporter implements Importer {
+    private static final String NAME_PREFIX = "Patient: ";
+
+    @Override
+    public Document importFile(final File file) throws IOException {
+        final TextFile textFile = new TextFile(file);
+        textFile.addLineSuffix(NAME_PREFIX, PATIENT);
+        textFile.addLines(2, line -> false, BODY);
+
+        final Map<String, String> attributes = textFile.getAttributes();
+        attributes.put(TYPE, "REPORT");
+        return new Document(attributes);
+    }
+}
diff --git a/book/real-world-software-development/chapter4/document-management/src/main/java/project/TextFile.java b/book/real-world-software-development/chapter4/document-management/src/main/java/project/TextFile.java
new file mode 100644
index 0000000..1b8feb0
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/src/main/java/project/TextFile.java
@@ -0,0 +1,58 @@
+package project;
+
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Predicate;
+
+
+import static java.util.stream.Collectors.toList;
+import static project.Attributes.PATH;
+
+class TextFile {
+    private final Map<String, String> attributes;
+    private final List<String> lines;
+
+    TextFile(final File file) throws IOException {
+        attributes = new HashMap<>();
+        attributes.put(PATH, file.getPath());
+        lines = Files.lines(file.toPath()).collect(toList());
+    }
+
+    Map<String, String> getAttributes() {
+        return attributes;
+    }
+
+    int addLines(
+            final int start,
+            final Predicate<String> isEnd,
+            final String attributeName) {
+
+        final StringBuilder accumulator = new StringBuilder();
+        int lineNumber;
+        for (lineNumber = start; lineNumber < lines.size(); lineNumber++) {
+            final String line = lines.get(lineNumber);
+            if (isEnd.test(line)) {
+                break;
+            }
+
+            accumulator.append(line);
+            accumulator.append("\n");
+        }
+        attributes.put(attributeName, accumulator.toString().trim());
+        return lineNumber;
+    }
+
+    void addLineSuffix(final String prefix, final String attributeName) {
+        for(final String line: lines) {
+            if (line.startsWith(prefix)) {
+                attributes.put(attributeName, line.substring(prefix.length()));
+                break;
+            }
+        }
+    }
+}
diff --git a/book/real-world-software-development/chapter4/document-management/src/main/java/project/UnknownFileTypeException.java b/book/real-world-software-development/chapter4/document-management/src/main/java/project/UnknownFileTypeException.java
new file mode 100644
index 0000000..2000173
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/src/main/java/project/UnknownFileTypeException.java
@@ -0,0 +1,7 @@
+package project;
+
+public class UnknownFileTypeException extends RuntimeException {
+    public UnknownFileTypeException(final String message) {
+        super(message);
+    }
+}
diff --git a/book/real-world-software-development/chapter4/document-management/src/test/java/chpater4/DocumentManagementSystemTest.java b/book/real-world-software-development/chapter4/document-management/src/test/java/chpater4/DocumentManagementSystemTest.java
new file mode 100644
index 0000000..676052a
--- /dev/null
+++ b/book/real-world-software-development/chapter4/document-management/src/test/java/chpater4/DocumentManagementSystemTest.java
@@ -0,0 +1,163 @@
+package chpater4;
+
+import org.junit.Test;
+import project.Document;
+import project.DocumentManagementSystem;
+import project.UnknownFileTypeException;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.util.List;
+
+
+import static project.Attributes.*;
+import static org.hamcrest.Matchers.hasSize;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+
+// tag::eg_constants[]
+public class DocumentManagementSystemTest
+{
+    private static final String RESOURCES =
+            "src" + File.separator + "test" + File.separator + "resources" + File.separator;
+    private static final String LETTER = RESOURCES + "patient.letter";
+    private static final String REPORT = RESOURCES + "patient.report";
+    private static final String XRAY = RESOURCES + "xray.jpg";
+    private static final String INVOICE = RESOURCES + "patient.invoice";
+    private static final String JOE_BLOGGS = "Joe Bloggs";
+
+// end::eg_constants[]
+
+    private DocumentManagementSystem system = new DocumentManagementSystem();
+
+    // tag::shouldImportFile[]
+    @Test
+    public void shouldImportFile() throws Exception
+    {
+        system.importFile(LETTER);
+
+        final Document document = onlyDocument();
+
+        assertAttributeEquals(document, PATH, LETTER);
+    }
+    // end::shouldImportFile[]
+
+    // tag::shouldImportLetterAttributes[]
+    @Test
+    public void shouldImportLetterAttributes() throws Exception
+    {
+        system.importFile(LETTER);
+
+        final Document document = onlyDocument();
+
+        assertAttributeEquals(document, PATIENT, JOE_BLOGGS);
+        assertAttributeEquals(document, ADDRESS,
+                "123 Fake Street\n" +
+                        "Westminster\n" +
+                        "London\n" +
+                        "United Kingdom");
+        assertAttributeEquals(document, BODY,
+                "We are writing to you to confirm the re-scheduling of your appointment\n" +
+                        "with Dr. Avaj from 29th December 2016 to 5th January 2017.");
+        assertTypeIs("LETTER", document);
+    }
+    // end::shouldImportLetterAttributes[]
+
+    @Test
+    public void shouldImportReportAttributes() throws Exception
+    {
+        system.importFile(REPORT);
+
+        assertIsReport(onlyDocument());
+    }
+
+    // tag::shouldImportImageAttributes[]
+    @Test
+    public void shouldImportImageAttributes() throws Exception
+    {
+        system.importFile(XRAY);
+
+        final Document document = onlyDocument();
+
+        assertAttributeEquals(document, WIDTH, "320");
+        assertAttributeEquals(document, HEIGHT, "179");
+        assertTypeIs("IMAGE", document);
+    }
+    // end::shouldImportImageAttributes[]
+
+    @Test
+    public void shouldImportInvoiceAttributes() throws Exception
+    {
+        system.importFile(INVOICE);
+
+        final Document document = onlyDocument();
+
+        assertAttributeEquals(document, PATIENT, JOE_BLOGGS);
+        assertAttributeEquals(document, AMOUNT, "$100");
+        assertTypeIs("INVOICE", document);
+    }
+
+    @Test
+    public void shouldBeAbleToSearchFilesByAttributes() throws Exception
+    {
+        system.importFile(LETTER);
+        system.importFile(REPORT);
+        system.importFile(XRAY);
+
+        final List<Document> documents = system.search("patient:Joe,body:Diet Coke");
+        assertThat(documents, hasSize(1));
+
+        assertIsReport(documents.get(0));
+    }
+
+    // tag::errorTests[]
+    @Test(expected = FileNotFoundException.class)
+    public void shouldNotImportMissingFile() throws Exception
+    {
+        system.importFile("gobbledygook.txt");
+    }
+
+    @Test(expected = UnknownFileTypeException.class)
+    public void shouldNotImportUnknownFile() throws Exception
+    {
+        system.importFile(RESOURCES + "unknown.txt");
+    }
+    // end::errorTests[]
+
+    private void assertIsReport(final Document document)
+    {
+        assertAttributeEquals(document, PATIENT, JOE_BLOGGS);
+        assertAttributeEquals(document, BODY,
+                "On 5th January 2017 I examined Joe's teeth.\n" +
+                        "We discussed his switch from drinking Coke to Diet Coke.\n" +
+                        "No new problems were noted with his teeth.");
+        assertTypeIs("REPORT", document);
+    }
+
+    // tag::assertAttributeEquals[]
+    private void assertAttributeEquals(
+            final Document document,
+            final String attributeName,
+            final String expectedValue)
+    {
+        assertEquals(
+                "Document has the wrong value for " + attributeName,
+                expectedValue,
+                document.getAttribute(attributeName));
+    }
+    // end::assertAttributeEquals[]
+
+    private void assertTypeIs(final String type, final Document document)
+    {
+        assertAttributeEquals(document, TYPE, type);
+    }
+
+    // tag::onlyDocument[]
+    private Document onlyDocument()
+    {
+        final List<Document> documents = system.contents();
+        assertThat(documents, hasSize(1));
+        return documents.get(0);
+    }
+    // end::onlyDocument[]
+}
diff --git a/javav-network/src/main/java/project/reflect/caculator/Calculator.java b/javav-network/src/main/java/project/reflect/caculator/Calculator.java
new file mode 100644
index 0000000..9a15466
--- /dev/null
+++ b/javav-network/src/main/java/project/reflect/caculator/Calculator.java
@@ -0,0 +1,5 @@
+package project.reflect.caculator;
+
+public class Calculator {
+    
+}
diff --git a/javav-network/src/main/java/project/was/httpserver/HttpRequest.java b/javav-network/src/main/java/project/was/httpserver/HttpRequest.java
new file mode 100644
index 0000000..d28ec2d
--- /dev/null
+++ b/javav-network/src/main/java/project/was/httpserver/HttpRequest.java
@@ -0,0 +1,4 @@
+package project.was.httpserver;
+
+public class HttpRequest {
+}
diff --git a/javav-network/src/main/java/project/was/httpserver/HttpResponse.java b/javav-network/src/main/java/project/was/httpserver/HttpResponse.java
new file mode 100644
index 0000000..96910b3
--- /dev/null
+++ b/javav-network/src/main/java/project/was/httpserver/HttpResponse.java
@@ -0,0 +1,4 @@
+package project.was.httpserver;
+
+public class HttpResponse {
+}
diff --git a/javav-network/src/main/java/project/was/httpserver/HttpServlet.java b/javav-network/src/main/java/project/was/httpserver/HttpServlet.java
new file mode 100644
index 0000000..10929e5
--- /dev/null
+++ b/javav-network/src/main/java/project/was/httpserver/HttpServlet.java
@@ -0,0 +1,4 @@
+package project.was.httpserver;
+
+public interface HttpServlet {
+}
diff --git a/javav-network/src/main/java/project/was/httpserver/ServletManager.java b/javav-network/src/main/java/project/was/httpserver/ServletManager.java
new file mode 100644
index 0000000..ad8df09
--- /dev/null
+++ b/javav-network/src/main/java/project/was/httpserver/ServletManager.java
@@ -0,0 +1,22 @@
+package project.was.httpserver;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class ServletManager {
+
+    private final Map<String, HttpServlet> servletMap = new HashMap<>();
+
+
+    public void add(String path, HttpServlet servlet){
+        servletMap.put(path, servlet);
+    }
+
+    public void execute(HttpRequest request, HttpResponse response){
+        try{
+
+        }catch (Exception e){
+
+        }
+    }
+}
diff --git a/javav-network/src/main/java/project/was/httpserver/servlet/NotFoundServlet.java b/javav-network/src/main/java/project/was/httpserver/servlet/NotFoundServlet.java
new file mode 100644
index 0000000..c26620c
--- /dev/null
+++ b/javav-network/src/main/java/project/was/httpserver/servlet/NotFoundServlet.java
@@ -0,0 +1,4 @@
+package project.was.httpserver.servlet;
+
+public class NotFoundServlet {
+}
diff --git a/javav-network/src/main/java/project/was/v3/PercentEncodingMain.java b/javav-network/src/main/java/project/was/v3/PercentEncodingMain.java
new file mode 100644
index 0000000..88641ed
--- /dev/null
+++ b/javav-network/src/main/java/project/was/v3/PercentEncodingMain.java
@@ -0,0 +1,17 @@
+package project.was.v3;
+
+import java.net.URLDecoder;
+import java.net.URLEncoder;
+import java.nio.charset.StandardCharsets;
+
+public class PercentEncodingMain{
+    public static void main(String[] args) {
+        String encode = URLEncoder.encode("가%", StandardCharsets.UTF_8);
+        System.out.println("encode = " +  encode);
+
+        String decode = URLDecoder.decode(encode, StandardCharsets.UTF_8);
+        System.out.println("decode = " + decode);
+
+
+    }
+}
diff --git a/javav-network/src/main/java/project/was/v5/servlet/HttpServlet.java b/javav-network/src/main/java/project/was/v5/servlet/HttpServlet.java
new file mode 100644
index 0000000..1bfae31
--- /dev/null
+++ b/javav-network/src/main/java/project/was/v5/servlet/HttpServlet.java
@@ -0,0 +1,4 @@
+package project.was.v5.servlet;
+
+public class HttpServlet {
+}
diff --git a/simple-java/docs/chapter4.md b/simple-java/docs/chapter4.md
new file mode 100644
index 0000000..d053f32
--- /dev/null
+++ b/simple-java/docs/chapter4.md
@@ -0,0 +1,5 @@
+## 문서관리 시스템
+
+### 도전 과제
+
+1. ㅛ5ㅛㅛㅛ
\ No newline at end of file
diff --git a/thread-pool-optimization/k6/io_user_test.js b/thread-pool-optimization/k6/io_user_test.js
index fec552c..433dde8 100644
--- a/thread-pool-optimization/k6/io_user_test.js
+++ b/thread-pool-optimization/k6/io_user_test.js
@@ -13,7 +13,13 @@ export let options = {
 export default function () {
     const res = http.get('http://localhost:8080/api/v1/users');
     check(res, {
-        'status is 200': (r) => r.status === 200,
+        'status is 200': (r) => {
+            const ok = r.status === 200;
+            if (!ok) {
+                console.log(`❌ 실패 응답: ${r.status} ${r.status_text}, headers: ${JSON.stringify(r.headers)}`);
+            }
+            return ok;
+        },
     });
     sleep(0.1);
 }
\ No newline at end of file
diff --git a/thread-pool-optimization/src/main/java/project/threadpooloptimization/interfaces/UserController.java b/thread-pool-optimization/src/main/java/project/threadpooloptimization/interfaces/UserController.java
index 37e75ed..2ba7f2e 100644
--- a/thread-pool-optimization/src/main/java/project/threadpooloptimization/interfaces/UserController.java
+++ b/thread-pool-optimization/src/main/java/project/threadpooloptimization/interfaces/UserController.java
@@ -6,6 +6,9 @@
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.method.HandlerMethod;
+import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter;
+import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;
 import project.threadpooloptimization.domain.UserResult;
 import project.threadpooloptimization.domain.UserService;
 
diff --git a/thread-pool-optimization/src/main/resources/application.yml b/thread-pool-optimization/src/main/resources/application.yml
index a3dec2e..59222bd 100644
--- a/thread-pool-optimization/src/main/resources/application.yml
+++ b/thread-pool-optimization/src/main/resources/application.yml
@@ -1,9 +1,9 @@
 server:
   tomcat:
     threads:
-      max: 50
+      max: 100
       min-spare: 10
-    accept-count: 100
+    #accept-count: 300
 
 spring:
   application: