[pytest-dev] process for replacing yield tests with modern style

[Chris Dent]

Several years ago I developed a relative simple YAML-based way of
doing HTTP tests. The processed turned yaml into tests and yielded
them for pytest to collect. At the time yield was the pytest
approved way of doing such things. That's here:

    https://github.com/tiddlyweb/tiddlyweb/blob/master/test/http_runner.py

A few years later I took that idea and turned it into gabbi[1].

Because of local constraints (OpenStack) gabbi needed to be unittest,
subunit and testrepository compliant and oriented. Only later, and in
rather a hurry, did I add pytest support, using the yield style that I
already knew.

It's a bit of hacky mess because the tests are ordered
unittest.TestCases inside a unittest.TestSuite that has fixtures in
the scope of the TestSuite. Each yaml file becomes a TestSuite.
For the pytest side of things, plugin code[2] uses the modifyitems
hooks to get the fixtures working effectively. Some "driver"[3] code
yields tests to a user-code[4] for loading the tests.

I recognize that this is all a bit messy, but it does the job. Now,
with the advent of pytest 3.x yield tests are deprecated and I'm not
sure of the correct way to get the same behavior in modern-style.

I'm aware of solutions for using yaml files themselves as the test
files[5] but that would be a problem for existing deployed tests
that use the style shown in [4] and would also require conftest.py
or command line arguments and what I'm hoping to maintain is a way
for unadorned discovery to work and for the gabbi tests to be fairly
integrated with other tests.

I can certainly migrate to the [5] style but I see this as a good
opportunity to learn more of the details of how pytest generates
tests and use it. Can anyone give me some pointers please?

Thanks very much.

[1] https://gabbi.readthedocs.io/
[2] https://github.com/cdent/gabbi/blob/master/gabbi/pytester.py
[3] https://github.com/cdent/gabbi/blob/2bd1c803b71bd26be7822be87e249a811467b863/gabbi/driver.py#L111
[4] https://github.com/cdent/gabbi/blob/master/gabbi/tests/test_gabbits_pytest.py
[5] http://docs.pytest.org/en/latest/example/nonpython.html#a-basic-example-for-specifying-tests-in-yaml-files

-- 
Chris Dent               ┬─┬ノ( º _ ºノ)        https://anticdent.org/
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