./bin/zopectl test -s Products.RichDocument
This would run all tests in the Products.RichDocument module. If you are using a buildout with an instance control script called instance, this would be:
./bin/instance test -s Products.RichDocument
Using buildout is probably a good idea - see the buildout tutorial - not at least because this is the only way that works reliably on Windows. We will use this syntax from now on.
To execute a single test or a set of tests matched by regular expression, you can use:
./bin/instance test -s Products.RichDocument -t setup
This would run tests in files like test_setup.py. To run all doctests in README.txt (presuming there was a test suite for this file) you would write:
./bin/instance test -s Products.RichDocument -t README.txt
The new test runner also includes a few debugging options. For example:
./bin/instance test -m Products.RichDocument -D
This will stop execution at the first failing test and drop into a PDB post-mortem.
To see the other options that are available, run:
./bin/instance test --help
When the tests you think are relevant all pass, it's time to run all tests and make sure nothing else broke. (No, we don't care that you are writing your code in a totally different python module than what those other tests are supposed to test, and that they were all fine and good and all you changed was a docstring. Run the tests when you think you're done.)
When tests finish running, you will see a report like:
... Ran 18 tests in 6.463s OK
(it may look slightly different, depending on which test runner you are using)
Rehearse a satisfied sigh as you read the line "OK", as opposed to seeing a count of failed tests. With time, this will be the little notifier that lets you go to bed, see your friends again or generally get back to real life with an svn commit.
If you're not so lucky, you may see:
Ran 18 tests in 7.009s FAILED (failures=1, errors=1)
(again, the output may look slightly different depending on your test runner, but the same information should always be there)
This means that there were 1 python error and 1 failed test during test execution.
A python error means that some of your test code, or some code that was called by a test, raised an exception. This is bad, and you should fix it right away.
A failed test means that your test was trying to assert something that turned out not to be true. This could be OK. It could mean you haven't written the code the test is testing yet (well done, you wrote the test first!), or that you don't yet know why it's failing. Sometimes you may be radically refactoring or rewriting parts of your code, and the tests will keep on failing until you're done. Incidentally, this is part of the reason why unit tests are so good - you can do that kind of stuff.
It's sometimes (not always - don't try this on Plone core unless you've been told it's OK by the release manager) acceptable to go to bed and check in a failing test if you are not in a position to know how to fix it. At least other developers will be aware of the problem and may be able to fix it.