Spring (@SpyBean) vs Mockito(@Spy)

Question

What is the difference between @SpyBean from org.springframework.boot.test.mock.mockito.SpyBean and @Spy from org.mockito.Spy?

Using @SpyBean instead of @Spy makes my tests fail.

Answer 1

@Spy doc says:

A field annotated with @Spy can be initialized explicitly at declaration point. Alternatively, if you don't provide the instance Mockito will try to find zero argument constructor (even private) and create an instance for you.

@SpyBean doc says:

Annotation that can be used to apply Mockito spies to a Spring ApplicationContext.

All beans in the context of the same type will be wrapped with the spy. If no existing bean is defined a new one will be added.

So the main difference is @SpyBean is a Spring Boot specific annotation but @Spy is part of Mockito itself. @SpyBean and @Spy basically do the same, but @SpyBean can resolve the Spring specific dependencies, e.g. @Autowired, @Spy can only create object with empty constructor.