Use assertTimeoutPreemptively to preserve JUnit 4 timeout semantics

[mattdepaula]

Summary

UpdateTestAnnotation migrated @Test(timeout=N) to @Timeout(N), which silently changes failure semantics:

• JUnit 4 (@Test(timeout=N)): test runs on a separate thread; runner unblocks after N ms via FutureTask.get(timeout) — a hanging test fails and the suite continues
• JUnit 5 (@Timeout(N), default SAME_THREAD): sends Thread.interrupt() to the test thread; if the test never checks for interruption (infinite loop, deadlock), the runner thread blocks forever

This PR replaces the @Timeout annotation with assertTimeoutPreemptively(Duration.ofMillis(N), () -> { body }), which runs the body on a separate thread and preemptively fails — preserving JUnit 4's original semantics. The pattern mirrors the existing @Test(expected=...) → assertThrows(...) body-wrap already implemented in this recipe.

Edge case handled: @Test(timeout=0) means "no timeout" in JUnit 4 (the default). The recipe skips the assertTimeoutPreemptively wrapping when timeout=0 and migrates the annotation only.

Upstream issue

openrewrite#1073

Behavior change

Before

// @Timeout SAME_THREAD — hanging test blocks runner thread forever
@Timeout(500)
public void test() { }

After

// assertTimeoutPreemptively — body on separate thread, preemptively fails after 500ms
@Test
public void test() {
    assertTimeoutPreemptively(Duration.ofMillis(500), () -> {
    });
}

Changes

• UpdateTestAnnotation: replace @Timeout emission with two-step assertTimeoutPreemptively body-wrap (mirrors assertThrows pattern); skip wrapping when timeout=0
• UpdateTestAnnotationTest:
  • annotationWithTimeout: updated expected output; added @Issue("#1073")
  • annotationWithTimeoutAndStatements: new test — non-empty method body is wrapped correctly
  • timeoutZeroIsNoOpInJUnit4SoAnnotationOnlyMigrated: new test — timeout=0 produces plain @Test, no body wrapping
  • annotationWithTimeoutAndException: updated expected output (nested assertThrows inside assertTimeoutPreemptively); added @Issue("#1073")

Test plan

• annotationWithTimeout — empty body, 500ms timeout
• annotationWithTimeoutAndStatements — non-empty body, 500ms timeout
• timeoutZeroIsNoOpInJUnit4SoAnnotationOnlyMigrated — timeout=0 skips wrapping
• annotationWithTimeoutAndException — combined expected + timeout, correct nesting
• All pre-existing UpdateTestAnnotationTest tests continue to pass

[timtebeek]

did you intend to open this as an upstream contribution as an alternative to

• Emit threadMode = SEPARATE_THREAD when migrating @Test(timeout = N) openrewrite/rewrite-testing-frameworks#1076 ?