Creating Stubs with gomock

gomock is able to create a stub just as well as a mock. If you want a stub that will always return a value for a given method call you use the AnyTimes() method:

ctrl := gomock.NewController(t)
defer ctrl.Finish()
m := NewMockFoo(ctrl)
m.
 EXPECT().
 Bar(gomock.Any()).
 Return(55).
 AnyTimes()

This will return 55 for any call to Bar(). But what if you need something a little more complex? What if you need it to return 66 if you pass in 6? Well gomock can easily do that as well!

ctrl := gomock.NewController(t)
defer ctrl.Finish()
m := NewMockFoo(ctrl)
m.
 EXPECT().
 Bar(gomock.Eq(6)).
 Return(66).
 AnyTimes()
m.
 EXPECT().
 Bar(gomock.Any()).
 Return(55).
 AnyTimes()

Note: The gomock.Any() case must be last. gomock keeps a slice of matchers (e.g., Any() vs Eq()) and then iterates over each . The gomock.Any() will always return true.