Trouble understanding how a mock is created

[luo weilue]

Hi people,

I am fairly new to mockito and I am trying understand how it works internally. By doing some navigations in ide, my current understanding of what happen when we call mock(someClass.class) is:

1. Mockito find a constructor of the given class (choose the first public if possible, else the first constructor).
2. Gather arguments for constructor: if arguments are not provided, use default values by argument types (e.g. false for boolean, 0 for int, null for object).
3. Use a MemberAccess class to create the new instance.
   • if class file version of VM is JAVA_V9 or above, this class is InstrumentationMemberAccessor.
     • I dont really understand this class.. create instance by load some custom .class bytecode that has some custom method handle (?)
   • else it is ReflectionMemberAccessor.
     • Return instance by invoking the given constructor with given argument.
4. Create the a MockMethodInterceptor that handles method invocation.
5. Store instance and method interceptor as key-value into a map called mocks.
6. ...Losing track, what happen next ? When we call mock.someMethod(), how it pass the invocation to the method interceptor?

If someone can give me some pointers it would be really helpful, thanks!

Best Regards,

Weilue