Discovery issue incorrectly reported for `abstract` inner class

[sbrannen]

Overview

In Spring Framework's test suite, I introduced a test fixture to replicate an issued reported by a user, where the user had a @Nested test class that extended an abstract inner class.

That is naturally supported and works fine; however, the new discovery issue reporting feature introduced in JUnit 5.13 incorrectly warns that such a declaration is invalid.

For example, when running MockitoBeanNestedAndTypeHierarchiesWithSuperclassPresentTwiceTests in spring-test, I see the following warning.

WARNING: TestEngine with ID 'junit-jupiter' encountered a non-critical issue during test discovery:

(1) [WARNING] Inner class 'org.springframework.test.context.bean.override.mockito.MockitoBeanNestedAndTypeHierarchiesWithEnclosingClassPresentTwiceTests$AbstractBaseClassForNestedTests' looks like it was intended to be a test class but will not be executed. It must be static or annotated with @Nested.
    Source: ClassSource [className = 'org.springframework.test.context.bean.override.mockito.MockitoBeanNestedAndTypeHierarchiesWithEnclosingClassPresentTwiceTests$AbstractBaseClassForNestedTests', filePosition = null]
            at org.springframework.test.context.bean.override.mockito.MockitoBeanNestedAndTypeHierarchiesWithEnclosingClassPresentTwiceTests$AbstractBaseClassForNestedTests.<no-method>(SourceFile:0)

Note that AbstractBaseClassForNestedTests is inherited from AbstractMockitoBeanNestedAndTypeHierarchiesWithSuperclassPresentTwiceTests, and it is intentionally not "static or annotated with @Nested."

Thus, I think the discovery issue check should be updated so that it does not report that, if the inner class in question is abstract.

Related Issues

• Discovery issue incorrectly reported for abstract @Test method in abstract class #4636

[sbrannen]

If the same test class is run via a @Suite, the following additional warning is also reported.

[WARNING] [junit-jupiter] Test class 'org.springframework.test.context.bean.override.mockito.MockitoBeanNestedAndTypeHierarchiesWithEnclosingClassPresentTwiceTests$AbstractBaseClassForNestedTests' must not be an inner class unless annotated with @Nested. It will not be executed (via @Suite org.springframework.test.context.SpringTestContextFrameworkTestSuite).
    Source: ClassSource [className = 'org.springframework.test.context.bean.override.mockito.MockitoBeanNestedAndTypeHierarchiesWithEnclosingClassPresentTwiceTests$AbstractBaseClassForNestedTests', filePosition = null]
            at org.springframework.test.context.bean.override.mockito.MockitoBeanNestedAndTypeHierarchiesWithEnclosingClassPresentTwiceTests$AbstractBaseClassForNestedTests.<no-method>(SourceFile:0)

Thus, I suppose there are two "discovery issue checks" that need to be adjusted.

@marcphilipp, if you'd prefer a separate GitHub issue for the @Suite use case, just let me know.

[sbrannen]

FWIW, annotating AbstractBaseClassForNestedTests with @Nested makes the warning disappear; however, I don't think we should require that abstract base classes be annotated with @Nested.