TestMethodsShouldBeVoid might fail with NullPointerException (NPE) on interfaces

[greg-at-moderne]

• Related to Add unit test showing null Methodinvocation type #870, Recipe to check that Kotlin test methods return Unit #871.

What version of OpenRewrite are you using?

current main of this repo = 9803871
OR = 8.68.1 or similar

What is the smallest, simplest way to reproduce the problem?

Add jspecify to test classpath resources:

+    testParserClasspath("org.jspecify:jspecify:1.0.0")

Rebuild test type tables:

./gradlew createTestTypeTable

In TestMethodsShouldBeVoidTest add jspecify:

-            .classpathFromResources(new InMemoryExecutionContext(), "junit-jupiter-api-5", "junit-jupiter-params-5"))
+            .classpathFromResources(new InMemoryExecutionContext(), "junit-jupiter-api-5", "junit-jupiter-params-5", "jspecify"))

And add the following test case:

    @Test
    void interfaces() {
        //language=java
        rewriteRun(
          java(
              """
              import org.jspecify.annotations.Nullable;

              public interface Doer {
                  @Nullable
                  String getFile(String input);
              }
              """
          )
        );
    }

Observed

            Caused by:
            java.lang.NullPointerException
                at java.base/java.util.Objects.requireNonNull(Objects.java:233)
                at org.openrewrite.java.testing.cleanup.TestMethodsShouldBeVoid$1.visitMethodDeclaration(TestMethodsShouldBeVoid.java:83)
                at org.openrewrite.java.testing.cleanup.TestMethodsShouldBeVoid$1.visitMethodDeclaration(TestMethodsShouldBeVoid.java:53)
                at org.openrewrite.java.tree.J$MethodDeclaration.acceptJava(J.java:4021)
                at org.openrewrite.java.tree.J.accept(J.java:55)
                at org.openrewrite.TreeVisitor.visit(TreeVisitor.java:242)
                ... 57 more

Commentary

I think there are at least two problems:

• one is assuming method body is not null (which might be not true for interfaces)
• the TEST_ANNOTATION_PATTERN false positive against org.jspecify.annotations.Nullable