Add Kotlin snippets for ten User Guide sections by yalishevant · Pull Request #5590 · junit-team/junit-framework

yalishevant · 2026-04-09T18:40:12Z

Adds Kotlin tabbed code snippets to ten more User Guide sections,
continuing the effort started in #5316 and #5432.

Pages updated (Writing Tests):

Built-in Extensions (@tempdir, @autoclose, Locale/TimeZone, SystemProperty)
Conditional Test Execution
Display Names
Annotations
Timeouts
Test Interfaces and Default Methods

Pages updated (Extensions):

Parameter Resolution
Keeping State in Extensions
Test Lifecycle Callbacks
Registering Extensions

I hereby agree to the terms of the JUnit Contributor License Agreement.

Definition of Done

There are no TODOs left in the code
~~Method preconditions are checked~~ (N/A — documentation only)
Coding conventions have been followed
Change is covered by automated tests
~~Public API has Javadoc and @API annotations~~ (N/A — documentation only)
Change is documented in the User Guide

@autoclose

Add tabbed Java/Kotlin code examples to ten documentation pages, continuing the effort started in junit-team#5316 and junit-team#5432. Pages updated (Writing Tests): - Built-in Extensions (@tempdir, @autoclose, Locale/TimeZone, SystemProperty) - Conditional Test Execution - Display Names - Annotations - Timeouts - Test Interfaces and Default Methods Pages updated (Extensions): - Parameter Resolution - Keeping State in Extensions - Test Lifecycle Callbacks - Registering Extensions Signed-off-by: Anton.Yalyshev <yalishev.ant@gmail.com>

marcphilipp

Thank you for the PR! 👍

marcphilipp · 2026-04-10T07:54:47Z

+    @Nested
+    // tag::default_timezone_class_level[]
+    @DefaultTimeZone("CET")
+    inner class MyTimeZoneTests {


I guess there's no way to hide the inner keyword because of the formatter? I think we have two options: include @Nested as well or move it to a separate file. Thoughts?

Went with including @Nested - moved the // tag:: markers before @Nested in both Java and Kotlin files so the annotation is now visible in the rendered snippets. This way the reader sees the full context without needing a separate file. IMO, some readers may find it useful. Let me know if you want to remove it from Java and keep only for Kotin.

marcphilipp · 2026-04-10T07:56:08Z

+    // tag::systemproperty_using_at_class_level[]
+    @ClearSystemProperty(key = "some property")
+    inner class MySystemPropertyTest {


Done - same fix applied here

marcphilipp · 2026-04-10T08:01:26Z

+        @TestInstance(TestInstance.Lifecycle.PER_CLASS)
+        // tag::systemproperty_class_restore_setup[]
+        @RestoreSystemProperties
+        inner class MySystemPropertyRestoreTest {


We should probably include the @TestInstance annotation here so one doesn't wonder why beforeAll() works. Same for the Java variant.

Good point - moved the // tag:: markers before @TestInstance(PER_CLASS) in both Java and Kotlin so readers can see why beforeAll() works without a companion object.

marcphilipp · 2026-04-10T08:02:01Z

+        // tag::systemproperty_class_restore_isolated_class[]
+        @ReadsSystemProperty
+        inner class SomeOtherTestClass {


marcphilipp · 2026-04-10T08:06:39Z

+--
+[source,kotlin,indent=0]
+----
+include::example$kotlin/example/kotlin/DisplayNameDemo.kt[tags=user_guide]


I wonder if we should a Kotlin-only example using backticks so spaced can be used in the function/test name directly. WDYT? 🤔

Sure, great idea - added a TIP block after the @DisplayName example mentioning Kotlin's backtick-enclosed function names as an alternative for simple display names, with a short inline code sample.

Or you would rather wanted to see it as one more function inside DisplayNameDemo class? It will break symmetry but save space 🙂

marcphilipp · 2026-04-10T08:17:35Z

+// tag::user_guide[]
+@Tag("timeout")


We're not showing the tag in the Java snippet. The formatter enforces this ordering so I guess the only thing we can do to make it consistent is to include it in the Java version as well.

Agreed - moved the // tag::user_guide[] marker before @Tag("timeout") in the Java file

marcphilipp · 2026-04-10T08:25:32Z

+    }
+
+    companion object {
+        @JvmStatic


There's not a strong reason for this method/function to be static. Let's make it non-static to simplify the Kotlin version.

Right - removed the companion object wrapper and @JvmStatic.

marcphilipp · 2026-04-10T08:26:11Z

 earlier versions and your extension stores resources that need to be cleaned up, you
 should implement both interfaces:

 [source,java,indent=0]


What about this one?

Thanks! Added a Kotlin tab for the inline MyResource example in the Migration Note. Used a longer delimiter ====== for the outer TIP block to allow nesting the [tabs] block inside it.

marcphilipp · 2026-04-10T08:33:31Z

+    @RegisterExtension
+    val docs: DocumentationExtension =
+        DocumentationExtension.forPath(lookUpDocsDir())


This needs @JvmField, doesn't it?

Suggested change

@RegisterExtension

val docs: DocumentationExtension =

DocumentationExtension.forPath(lookUpDocsDir())

@JvmField

@RegisterExtension

val docs =

DocumentationExtension.forPath(lookUpDocsDir())

You're right! Added @JvmField before @RegisterExtension. Thank you

marcphilipp · 2026-04-10T08:35:51Z

+class TimingExtension :
+    BeforeTestExecutionCallback,
+    AfterTestExecutionCallback {
+    private val logger: Logger = Logger.getLogger(TimingExtension::class.java.name)


Move into companion object?

Right, it mirrors private static final semantics

@nested

- Include @nested, @testinstance, @tag in tag scope - Add Kotlin tab for inline MyResource snippet in TIP block - Add @JvmField on @RegisterExtension instance field - Move logger to companion object in TimingExtension - Remove unnecessary companion object from sendRequest - Add Kotlin-only TIP for backtick test names in display-names Signed-off-by: Anton.Yalyshev <yalishev.ant@gmail.com>

testlens-app · 2026-04-16T14:16:52Z

✅ All tests passed ✅

🏷️ Commit: 8b5d49b
▶️ Tests: 810 executed
⚪️ Checks: 15/15 completed

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yalishevant force-pushed the kotlin-snippets-batch3 branch from 8a1b05b to 6128746 Compare April 9, 2026 18:50

marcphilipp added this to the 6.1.0-M2 milestone Apr 10, 2026

marcphilipp self-requested a review April 10, 2026 06:56

marcphilipp reviewed Apr 10, 2026

View reviewed changes

yalishevant force-pushed the kotlin-snippets-batch3 branch from 529d18f to 6128746 Compare April 16, 2026 13:53

yalishevant requested a review from marcphilipp April 16, 2026 14:43

		// tag::user_guide[]
		@Tag("timeout")

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testlens-app bot commented Apr 16, 2026

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