Why @InjectMocks Does Not Support Mixed Dependency Injection?

[reddi prit]

Recently I encountered a problem when I wrote a Junit test case using Mockito. I got to know that it happened because I used mixed dependency in Google Guice. I used constructor & setter injection both in my test class. The dependency injected by setter became null when I tried used @InjectMocks annotation on my test class.

I found out the problem & workaround thanks to this post https://www.w3spot.com/2022/02/mocked-dependency-object-is-null-after-using-mockito-injectmocks-annotation.html

But I am not able to understand why Mockito designed it like this. Mixed dependency works when I use MockitoAnnotations.initMocks(), but not with @InjectMocks. Both should work same way, either support mixed dependencies or not. Anyone knows why?