Move TogglzTestExecutionListener out of togglz-spring-core module

[hantsy]

When adding starter into the project, the TogglzTestExecutionListener will be enabled by default for tests, and it is better to move it standalone module(eg. togglz-spring-test) and allow developers to add it manually.

Additionally when I try to mock FeatureManager in my tests it always fails my mocks.

[bennetelli]

You actually don't have to mock it. Togglz ships with a special module for unit testing feature toggles: https://www.togglz.org/documentation/testing.html

[hantsy]

I know well about this testing feature provided by togglze, but in our controller test, I would like to isolate any dependencies and focus on request/response verfication.

Unfortunately, we can not mock featureManager there due to the togglz TestExecutionListener.

[hantsy]

And if I provide custom State Repository, User Repository, Activation Strategy implementations, and then the togglz testing harness becomes heavy, I do not want to hit database when testing controllers.

[hantsy]

When added togglz spring boot stater and use FeatureManager(Spy or inject, I can not mock due to the listener) in tests, this listener will fail a lot of my tests.

I also created an issue on Spring framework to avoid the useless test listeners that affected my tests. spring-projects/spring-framework#30321

[sbrannen]

As I mentioned in spring-projects/spring-framework#30321 (comment):

... in the Spring TestContext Framework we recommend that listeners and customizer factories "only do something when they're supposed to do something."

...

Whereas, TogglzTestExecutionListener (almost?) always modifies the internal state of a FeatureManager bean, if present in the ApplicationContext.

To best support users with varying use cases, TogglzTestExecutionListener should only modify the state of a bean in the ApplicationContext if the user requests that -- for example, via a Togglz-specific annotation on the test class.

Phrased differently, the mere presence of the TogglzTestExecutionListener in the classpath should not result in the state of a bean in the ApplicationContext being modified automatically without the user requesting that.

In light of that, perhaps the Togglz team would consider introducing a test annotation to control/trigger the behavior of the TogglzTestExecutionListener.