JUnit5 support

[chennu2020]

JUnit 5 support for Java SDK with backward compatibility.

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R: @chamikaramj for label java.

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Reminder, please take a look at this pr: @chamikaramj

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Assigning new set of reviewers because Pr has gone too long without review. If you would like to opt out of this review, comment assign to next reviewer:

R: @Abacn for label java.

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[Abacn]

tracking bug: #18733.

Thanks for taking this long standing issue forward. And agree with the approach of supporting both junit 4/5 for compatibility.

I would suggest taking the chance to revisit the situation of Beam java core depending on junit/hamcrest and other test dependencies. There is plan to separate non-core dependencies out of Java core: #34554 at least we can do for new junit5 dependencies. (Currently every Beam java user have these test dependencies even for production pipeline which is not ideal).

I would recommend to create a new module e.g. sdks/java/testing/junit (naming can be discussed) dedicated for junit 5 test pipelines, and put TestPipelineExtensions there. Utimately we may move TestPipeline and any test fixtures out of Java core (but this is a breaking change, so probably in Beam 3)

[liferoad]

/gemini review

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Code Review

This pull request introduces JUnit 5 support for the Java SDK, which is a great enhancement for modernizing the testing framework. The implementation includes a new TestPipelineExtension for JUnit 5, updates to the build files, and documentation. My review focuses on the correctness of the build configuration and the maintainability of the new extension.

I've identified a high-severity issue in the build.gradle file where useJUnit() is used instead of useJUnitPlatform(), which will prevent JUnit 5 tests from running. I've also pointed out a medium-severity maintainability issue in TestPipelineExtension.java regarding the use of Optional in the ExtensionContext.Store, with a suggestion for refactoring.

[Abacn]

Thank you!

[idc101]

I am trying to use this in v2.68 but the validation is still looking for the junit 4 Rule:

Is your TestPipeline declaration missing a @Rule annotation? Usage: @Rule public final transient TestPipeline pipeline = TestPipeline.create();
java.lang.IllegalStateException: Is your TestPipeline declaration missing a @Rule annotation? Usage: @Rule public final transient TestPipeline pipeline = TestPipeline.create();
	at org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkState(Preconditions.java:512)
	at org.apache.beam.sdk.testing.TestPipeline.run(TestPipeline.java:414)
	at org.apache.beam.sdk.testing.TestPipeline.run(TestPipeline.java:366)

Recreate with:

import org.apache.beam.sdk.testing.NeedsRunner;
import org.apache.beam.sdk.testing.TestPipeline;
import org.apache.beam.sdk.testing.TestPipelineExtension;
import org.junit.experimental.categories.Category;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;

 @ExtendWith(TestPipelineExtension.class)
 public class DeDuplicateTest implements Serializable {
    @Test
    @Category(NeedsRunner.class)
    public void testBasicDeDuplicate(TestPipeline p) {
        p.run();
    }

[Abacn]

I am trying to use this in v2.68 but the validation is still looking for the junit 4 Rule:

Fixed in #36258. Unfortunately this new module isn't functioning in Beam 2.68. Will be fixed in the next release.