Mocking session scoped spy bean calls real method

[cdalexndr]

Trying to mock a @SessionScope in a test by autowiring it using @SpyBean and then mocking using doReturn(..).when(sessionScopedBean).method(any()) calls the real method with null argument instead of silently registering mock.
Removing @SessionScope from the bean resolves this issue.

Spring boot 2.1.6.RELEASE

[mbhave]

@cdalexndr Please provide a minimal sample that we can use to reproduce the issue.

[cdalexndr]

https://github.com/cdalexndr/spring-boot-issue-17817
Just run gradlew test
Note that removing @SessionScope fixes test.

[blindpirate]

I did some debugging. Seems like that @SessionScope is enhanced by Spring so every method in it becomes final, thus Mockito can't enhance it again. I'm wondering, why does Spring make all methods final when enhancing the bean? Can we somehow only make the injected methods final, but keep all declared methods non-final?

[wilkinsona]

Thanks for the sample, @cdalexndr.

When you use @SpyBean, the spy is created via SpyPostProcessor which is an InstantiationAwareBeanPostProcessorAdapter and it is PriorityOrdered with highest precedence. This is intended to ensure that the spy is created before any proxying performed by Spring Framework. It works for @Scheduled, @Async, etc, but it does not work in the case of a scoped proxy as the proxying is done as part of component scanning rather than bean post-processing. Switching to a @Bean method on a @Configuration class does not help as ConfigurationClassBeanDefinitionReader does the same thing.

I can't see a way to fix this without some changes in Spring Framework. Flagging for team attention in case I've missed something.

[wilkinsona]

We might be able to get the bean definition for the target as both it and the scoped proxy are added to the bean factory. We could perhaps then replace the target with the definition for the spy.