Abstract classes with `@Nested` are not ignored / not handled properly

[Marcono1234]

Description

The predicate for whether a class annotated with @Nested can be executed does not check whether the class is abstract, see IsNestedTestClass. This causes a java.lang.InstantiationException when trying to run the tests (from within Eclipse IDE).

The predicate for top level test classes in IsPotentialTestContainer excludes abstract classes.

In case you decide to indeed ignore abstract nested classes, then error handling for that would probably have to be part of #242.

Steps to reproduce

Try to run the following test:

package test;

import org.junit.jupiter.api.Nested;
import org.junit.jupiter.api.Test;

public class NestedTestClass {
    @Nested
    public abstract class NestedClass {
        @Test
        public void test() {
            System.out.println("test");
        }
    }
}

Context

• Used versions (Jupiter/Vintage/Platform): 5.8.0
• Build Tool/IDE: Eclipse IDE 2021-06 (4.20.0)

[sbrannen]

What is the use case for having an abstract @Nested test class?

@Nested is not @Inherited, so it cannot apply to a subclass of an abstract @Nested test class.

[sbrannen]

What is the use case for having an abstract @Nested test class?

Or are you claiming there is no use case and that you would prefer a better (more informative) error message?

[Marcono1234]

Or are you claiming there is no use case and that you would prefer a better (more informative) error message?

Yes that was what I meant. Either a better error message or such classes being ignored (similar to other cases mentioned in #242). Personally I would prefer an error to make the user aware of the issue, since it is not known yet when 242 will be resolved.

[marcphilipp]

Team decision: Let's introduce a proper error message for this scenario when tackling #242.