#128: add cutOff function

src/main/kotlin/utils/StringUtils.kt

@@ -0,0 +1,6 @@
+package utils
+
+fun String.cutOff(maxCharsPerLine: Int): String {
+    require(maxCharsPerLine > 0) { "Character limit should be at least 1" }
+    return if (length <= maxCharsPerLine) this else "${take(maxCharsPerLine - 1)}…"
+}

src/test/kotlin/utils/StringUtilsKtTest.kt

@@ -0,0 +1,42 @@
+package utils
+
+import io.kotest.assertions.throwables.shouldThrow
+import io.kotest.matchers.equals.shouldBeEqual
+import org.junit.jupiter.api.Test
+
+class StringUtilsKtTest {
+    @Test
+    fun `when string is less than max character limit, then return same string`() {
+        val input = "testyy"
+        input.cutOff(100).shouldBeEqual(input)
+    }
+
+    @Test
+    fun `when string is longer than max character limit, then return truncated string with ellipsis`() {
+        val input = "Testyyyyyyyyyyyyyyyyyyyy"
+        input.cutOff(5).shouldBeEqual("Test…")
+    }
+
+    @Test
+    fun `when max character limit is negative, then throw exception`() {
+        val exception =
+            shouldThrow<IllegalArgumentException> {
+                "willCrash".cutOff(-10)
+            }
+        exception.message?.shouldBeEqual("Character limit should be at least 1")
+    }
+
+    @Test
+    fun `when max character limit is 0, then throw exception`() {
+        val exception =
+            shouldThrow<IllegalArgumentException> {
+                "willCrash".cutOff(0)
+            }
+        exception.message?.shouldBeEqual("Character limit should be at least 1")
+    }
+
+    @Test
+    fun `when max character limit is 1, then return ellipsis character`() {
+        "testy".cutOff(1).shouldBeEqual("…")
+    }
+}