TestCommand is the abstract base class for all test commands in the framework. A TestCommand represents a single stage in the execution of a test, e.g.: SetUp/TearDown, checking for Timeout, verifying the returned result from a method, etc. TestCommands may decorate other test commands so that the execution of a lower-level command is nested within that of a higher level command. All nested commands are executed synchronously, as a single unit. Scheduling test execution on separate threads is handled at a higher level, using the task dispatcher.