For every new feature, unit tests should be created that both test and (implicitly) document the usage of said feature. If submitting a patch for a bug that had no unit test, a new passing unit test should be added. If a submitted bug fix does have a unit test, be sure to add a new one that fails without the patch and passes with the patch.
The testing system is based on a combination of tox and stestr. The canonical approach to running tests is to simply run the command
tox. This will create virtual environments, populate them with dependencies and run all of the tests that OpenStack CI systems run. Behind the scenes, tox is running
stestr run, but is set up such that you can supply any additional stestr arguments that are needed to tox. For example, you can run:
tox -- --analyze-isolation to cause tox to tell stestr to add --analyze-isolation to its argument list.
It is also possible to run the tests inside of a virtual environment you have created, or it is possible that you have all of the dependencies installed locally already. In this case, you can interact with the stestr command directly. Running
stestr run will run the entire test suite.
stestr run --concurrency=1 will run tests serially (by default, stestr runs tests in parallel). More information about stestr can be found at: http://stestr.readthedocs.io/