Google Mock provides built-in support for mocks, provides a good Hamcrest library, and appears to be widely used.
Google Mock provides inadequate support for test suites. While Google Mock does provide the ability to execute a subset of tests using a command-line filter, it provides no direct support for permanently defining suites. (You could circumvent this deficiency by redirecting input from a series of files.)
The default test run output from Google Mock provides information on all tests, unfortunately. In a large suite, the volume of output describing successfully executed tests will make it difficult to find information on failed tests without command-line manipulation.
To counter this problem, you can create a custom test event listener in a matter of minutes that produces simplified output for a Google Test execution. See https://code.google.com/p/googletest/wiki/AdvancedGuide#Extending_Google_Test_by_Handling_Test_Events for further details.
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