Missing use case for 'rule to handle more than one test class matching impl class'

[krzysztof-owczarek]

Linked to: #920

Structure like this:

com/tngtech/archunit/library/testclasses/packages/correct/onlyoneimplmatchingdir1/OnlyOneImplementationHaveTestAndItIsMatchingImplPackage.java
com/tngtech/archunit/library/testclasses/packages/correct/onlyoneimplmatchingdir1/OnlyOneImplementationHaveTestAndItIsMatchingImplPackageTest.java
com/tngtech/archunit/library/testclasses/packages/incorrect/onlyoneimplmatchingdir2/OnlyOneImplementationHaveTestAndItIsMatchingImplPackage.java

will fail test:

    @Test
    public void should_pass_when_only_one_of_two_implementations_have_test_class_and_it_is_in_implementation_package() {
        assertThatRule(testClassesShouldResideInTheSamePackageAsImplementation())
                .checking(new ClassFileImporter().importPackagesOf(
                        OnlyOneImplementationHaveTestAndItIsMatchingImplPackage.class,
                    com.tngtech.archunit.library.testclasses.packages.incorrect.onlyoneimplmatchingdir2.OnlyOneImplementationHaveTestAndItIsMatchingImplPackage.class
                ))
                .hasNoViolation();
    }

Right now it seems that if one of the implementation has a test in the correct package and the other one (with the same name) has no test at all, the possibleTestClasses will find the test in the wrong package and fail the rule. You have to add at least a blank test class in the right package for each implementation to make the rule pass.

Possible solution could be:

• keeping track of the implementation class list,
• checking if the possibleTestClasses have no matching implementation in the right package and discard it from checklist of another implementation class.