@MockBean combined with @Repeat results in "the field cannot have an existing value" error

[alexey-anufriev]

I need to run Spring Test concurrently. For this reason, a separate method rule has been created.
The logic of this rule (code included in reproducer) is to execute the test method multiple times in a dedicated executor.

Unfortunately injection flow does not work as excepted and throws the following exception:

org.springframework.beans.factory.BeanCreationException: Could not inject field: <xxx>; 
    nested exception is java.lang.IllegalStateException: The field <xxx> cannot have an existing value
	at org.springframework.boot.test.mock.mockito.MockitoPostProcessor.inject(MockitoPostProcessor.java:364)

Reproducer and instruction are here: https://github.com/alexey-anufriev/spring-test-concurrent-execution-problem

[wilkinsona]

For reference, this was originally discussed on Gitter.

[philwebb]

Unfortunately I don't think the approach you're trying to take will work for mocked beans. The ConcurrentTestStatement is calling the evaluate method multiple times which is trying to call TestContextManager.prepareTestInstance multiple times with the same instance. My understanding is that this method is usually called only once, and with unique instances that are created by JUnit before the test method is run.

Even if we didn't have the "field cannot have an existing value" check, I think you'd hit trouble with the Mockito stubbing. The when(this.someBean.getData()).thenReturn("some other data") statement could be called multiple times in different threads and each would be trying to work on the same someBean instance. Things would get even worse if you had multiple @ConcurrentTest methods trying to setup different stubbing rules.

I'm not really sure what to suggest you try. It feels like you probably needs a fresh ApplicationContext for each invocation of a @ConcurrentTest method. Perhaps @sbrannen might have some ideas.

[philwebb]

I'm going to close this one here because I don't think there's anything we can do in Spring Boot to help.

[alexey-anufriev]

@philwebb, this approach has actually being inspired by @Repeat annotation. But I think @Repeat will also not work. Just tried to replace @ConcurrentTest with @Repeat and got the same error. So maybe we can adjust this issue to fix @Repeat and consequently can find a way to make it work with @Concurrent.