Begin Unit Test Client that holds object in memory to be used as client mock.

UnitTestDeleteErrorClient is a UnitTestClient whose Delete method fails.

UnitTestGetErrorClient is a UnitTestClient whose Get method fails.

UnitTestListErrorClient is a UnitTestClient whose List method fails.

UnitTestStatusErrorClient is a UnitTestClient whose Status method return a UnitTestStatusErrorWriter.

UnitTestStatusErrorWriter is a StatusWriter whose Update method fails.