`@SpyBean` can be stubbed, but `@MockitoSpyBean` cannot be stubbed

[JavaDevaraj]

In Spring Boot 3.3:

@SpyBean
private ReprocessBackOffImpl reprocessBackOffImpl;

doThrow(exception).when(reprocessBackOffImpl).assertPreConditions(context);

It's working fine....

but after upgrading to Spring Boot 3.4:

@MockitoSpyBean
private ReprocessBackOffImpl reprocessBackOffImpl;

doThrow(exception).when(reprocessBackOffImpl).assertPreConditions(context);

I'm getting the following exception.

Argument passed to when() is not a mock!
Example of correct stubbing:
    doThrow(new RuntimeException()).when(mock).someMethod();
org.mockito.exceptions.misusing.NotAMockException: 
Argument passed to when() is not a mock!

[sbrannen]

Hi @JavaDevaraj,

That exception can occur when reprocessBackOffImpl is either null or not a mock/spy.

If it's null, that's probably because you are using @MockitoSpyBean on a field somewhere other than in a test class.

If it's non-null and still not a mock/spy, that would could be due to a bug (which may have already been fixed).

In light of the above, your issue could be a duplicate of one of the following.

• Support @MockitoBean in @Configuration classes #33934
• MockReset strategy is no longer honored for @MockitoBean and @MockitoSpyBean #33941
• @MockitoBean is not supported in @Component class like @MockBean is #34415

Unfortunately, the examples you have provided do not provide any context. We have no way of inferring where you declared the @MockitoSpyBean field or where you attempted to stub it with doThrow().

Please review the aforementioned issues to see if one of those addresses your issue.

If you wish for us to investigate this further, please provide a simple application that demonstrates the issue (preferably something that we can download and run such as a an application in a public Git repository or a ZIP file attached to this issue).

Regards,

Sam

[quaff]

@JavaDevaraj Please note @MockitoSpyBean will not create bean instance if existing bean not found while @SpyBean does.

see #33935

[spring-projects-issues]

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