mock: fix erroneous calledWithArgs messages

[kleinerhund]

Summary

AssertCalled(...) displays output from other methods when the assertion fails.

Changes

Added a check that the called method name matches that of the asserted method name. Same as in AssertNumberOfCalls(...).

Motivation

AssertCalled(...) fails for the correct assertion, however the output displayed can sometimes indicate that the method was called with arguments from other methods.

Related issues

Closes #1144