Chris Dent d858e8379c Add docs explaining use of new pytest technique

loader.rst has been expanded to explain both ways for loading
tests using pytest, hopefully with sufficient context to explain
why it is like it is.

With any luck this will help make the obvious cleaner solution
more apparent as we iterate into the future.

2016-11-28 21:02:38 +00:00

3.8 KiB

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Loading and Running Tests

To run gabbi tests with a test harness they must be generated in some fashion and then run. This is accomplished by a test loader. Initially gabbi only supported those test harnesses that supported the load_tests protocol in UnitTest. It now possible to also build and run tests with pytest with some limitations described below.

Note

It is also possible to run gabbi tests from the command line. See runner.

Warning

If test are being run with a runner that supports concurrency (such as testrepository) it is critical that the test runner is informed of how to group the tests into their respective suites. The usual way to do this is to use a regular expression that groups based on the name of the yaml files. For example, when using testrepository the .testr.conf file needs an entry similar to the following:

group_regex=gabbi.suitemaker.(test[^_]+_[^_]+)

UnitTest Style Loader

To run the tests with a load_tests style loader a test file containing a load_tests method is required. That will look a bit like:

example.py

For details on the arguments available when building tests see ~gabbi.driver.build_tests.

Once the test loader has been created, it needs to be run. There are many options. Which is appropriate depends very much on your environment. Here are some examples using unittest or testtools that require minimal knowledge to get started.

By file:

python -m testtools.run -v test/test_loader.py

By module:

python -m testttols.run -v test.test_loader

python -m unittest -v test.test_loader

Using test discovery to locate all tests in a directory tree:

python -m testtools.run discover

python -m unittest discover test

See the source distribution and the tutorial repo for more advanced options, including using testrepository and subunit.

pytest

Since pytest does not support the load_tests system, a different way of generating tests is required. Two techniques are supported.

The original method (described below) used yield statements to generate tests which pytest would collect. This style of tests is deprecated as of pytest>=3.0 so a new style using pytest fixtures has been developed.

pytest >= 3.0

In the newer technique, a test file is created that uses the pytest_generate_tests hook. Special care must be taken to always import the test_pytest method which is the base test that the pytest hook parametrizes to generate the tests from the YAML files. Without the method, the hook will not be called and no tests generated.

Here is a simple example file:

pytest3.0-example.py

This can then be run with the usual pytest commands. For example:

py.test -svx pytest3.0-example.py

pytest < 3.0

When using the older technique, test file must be created that calls ~gabbi.driver.py_test_generator and yields the generated tests. That will look a bit like this:

pytest-example.py