Thanks for raising this issue before 5.3 GA!

I am not yet certain if it's a "bug"; however, I am going to label it as a bug for the time being to ensure that it gets looked at with high priority.

OK. I took at look at the code in question.

This is the expected behavior.

A @Nested test class cannot change the @TestInstance lifecycle mode declared for an enclosing class.

Thus, in your example, ServiceTest5 retains its declared PER_CLASS lifecycle mode regardless of any declarations for a different lifecycle mode on a nested test class.

Please note that this behavior is specific to the semantics for @TestInstance lifecycle and therefore not directly related to the new TestInstanceFactory extension API.

I am therefore closing this issue as "works as designed".

Thank you, but that is unexpected, so inner classes may not override the Lifecycle, or only if the outer is PER CLASS? Shouldn't this lead to an error, since the results are unexpected?

I suppose whether it's expected behavior or not is debatable, but that is the behavior the JUnit Team decided on when the feature was implemented.

A @Nested test class can be configured with its own lifecycle mode which may differ from that of an enclosing test class.

A @Nested test class cannot change the lifecycle mode of an enclosing test class.

The general rule is that each test class (whether top-level, nested, or a subclass) decides for itself what its lifecycle mode should be. The only form of inheritance with regard to lifecycle modes is that subclasses inherit the mode from their parent class by default.

Just to clarify:
" JUnit creates a new instance of each test class before executing each test method" in case of PER_METHOD in inner classes means that the current instance of the inner class is recreated every call of a method, but in case of outer-class "PER_CLASS" not the instance of the outer class. The creation of inner classes are not done via the TestInstanceFactory.

Btw. Thank you very much for the quick responses.

@aschoerk said:

The creation of inner classes are not done via the TestInstanceFactory.

They can be, because JUnit 5 has a unit test which shows it. The problem is when the same TestInstanceFactory is used on the outer and inner classes: #1567

Just to clarify: " JUnit creates a new instance of each test class before executing each test method" in case of PER_METHOD in inner classes means that the current instance of the inner class is recreated every call of a method, but in case of outer-class "PER_CLASS" not the instance of the outer class.

That's correct.

The creation of inner classes are not done via the TestInstanceFactory.

They should be if there is a TestInstanceFactory registered for the @Nested test class.

Btw. Thank you very much for the quick responses.

You're welcome.