Silence mock.go logs when using AssertExpectations

[dsvensson]

I have a suite which owns a mock instance that gets recreated in each SetupTest(). To avoid copy-paste laziness that introduces superflous mock.On calls, I added AssertExpectations to suite's TearDownTest() function. This is great as it catches all unused On calls, but it has the side effect of adding log message for each time a function is called on the mock. What's the reason for this log message? Could it perhaps go away?