Conditional extension registration via @ExtendWith

[Lubetkin]

I have a use case where I have a custom annotation i.e. @MyAnnotation that is annotated by @ExtendWith(Extension.class).

On a test method, I declare @MyAnnotation and another annotation, @OtherAnnotation.

@MyAnnotation
@OtherAnnotation
void test(){...}

I want to be able to deactivate the extension registered in MyAnnotation (Extension.class) when the second annotation, OtherAnnotation is present, because JUnit Jupiter takes the extension from MyAnnotation and runs it, but I want that MyAnnotation could be used as a self contained annotation in other test cases.

Is there a way to tell if OtherAnnotation is present and not run the Extension.class in MyAnnotation?

[sormuras]

Implement a check in MyAnnotation that tests for the presence of OtherAnnotation (on the same annotatable element) and make MyAnnotation perform a "no operation"?

Use ExtensionContext.getElement() to get a handle of the annotated element.

[Lubetkin]

I want it as an infrastructure for all annotations that being set with MyAnnotation. that was a simple example. Are you saying that each annotation need to implement this "no operation" code?

[marcphilipp]

Can you provide some more details on your use case? To me, having an annotation change its meaning when another annotation is present sounds confusing.

[Lubetkin]

@marcphilipp

@myannotationA
@otherannotation
void test1(){...}

@myannotationB
@otherannotation
void test2(){...}

@myannotationA
void test3(){...}

@myannotationB
void test4(){...}

test1 will ignore myannotationA extensions registered in ExtendWith because otherAnnotation is executing those extensions.

test2 the same as test1, will ignore myannotationB extensions registered in ExtendWith because otherAnnotation is executing those extensions.

test3 and test4 will execute the extensions from the above annotations because otherAnnotation is missing.

I want to be able to do it in an infrastructure level and not like was proposed here that every annotation logic will check if otherAnnotation exists or not.

[sbrannen]

Is there a way to tell if OtherAnnotation is present and not run the Extension.class in MyAnnotation?

No, there is no built-in mechanism for doing something like this.

In other words, JUnit Jupiter does not have support for "conditional extension registration" -- which is how I would phrase your request.

Rather, as @sormuras pointed out, you would have to implement the conditional logic within your extension implementations, effectively performing a no-op if your "higher ranking" annotation is also present.

[sbrannen]

On a test method, I declare @MyAnnotation and another annotation, @OtherAnnotation.

Why?

Why would you expect users to be able to (or want to) declare @MyAnnotation and @OtherAnnotation simultaneously if @OtherAnnotation always overrides @MyAnnotation?

Why not just instruct users to declare either @MyAnnotation or @OtherAnnotation?

If you truly need conditional configuration, why not just have a single annotation that accepts configuration values (i.e., via annotation attributes) and then have a single extension that does the right thing according to the user's configuration in that single annotation?

[sbrannen]

FYI: I reworded the title of this issue to reflect the scope of the discussion.

[Lubetkin]

@sbrannen
Because the OtherAnnotation is a common annotation that is being used by other test modules. And MyAnnotation is per test module.
I have an option to pass a list of extension to that annotation but want to minimize the boilerplate of that list by abstracting it in another annotation and also for reusable annotation to be used without the common one.

[sbrannen]

Hmmmm.... the discussion here is a bit too abstract for me.

Can you perhaps shed some light on the actual use case you have?

That would make it easier for us to understand and perhaps easier for us to make an alternative proposal.

[Lubetkin]

I want to pass to the extension state in OtherAnnotation a list of extension that are stated in MyAnnotation to execute as well.
the extension state in OtherAnnotation is a test template and I need the ability to add those extensions to the test template as an additional extensions.
And the ability to use those extensions state in MyAnnotation as self contained annotation as well.

[sormuras]

You could share some common state via the global store:

• http://junit.org/junit5/docs/current/user-guide/#extensions-keeping-state