Currently, all driver tests except the instance test wind up in a single "driver" test binary. Also, tests sources are jumbled together in a single directory. It may also be that there are a mix of mocked and non-mocked tests in a single file. This makes it hard to know what failed when the test fails and hard to know where to find integration and unit tests in the source.

I think it would be a lot clearer to divide test binaries as follows:

• unit – unit tests that do not rely on mocking, e.g. options class tests
• mock – unit tests that require mocking libmongoc functions
• integration – tests that require a mongod

Similarly, test sources should be divided along similar lines, possibly into separate directories.