Embodiments of the invention provide a method, system and computer program product for fault alerting in mock object supported unit testing. In an embodiment of the invention, a method for fault alerting in mock object supported unit testing is provided. The method includes creating in memory of a computing system an instance a mock object proxying for an object under test by test code and proxying by method name an invocation of a method in the object under test to the mock object. The method also includes determining whether or not a method exists in memory for the mock object corresponding to the method name. Finally, the method includes invoking an exception handler for the mock object outputting error text indicating a non-presence of a method associated with the method name responsive to a method by the method name not existing in the memory for the mock object, but otherwise invoking a method that exists in the memory of the mock object corresponding to the method name.