Context
I am updating an inherited repository which has poor test coverage. The repo itself is a pytest plugin. I've changed the repo to use tox along with pytest-cov, and converted the "raw" tests to use pytester as suggested in the pytest documentation when testing plugins.
The testing and tox build, etc. works great. However, the coverage is reporting false misses with things like class definitions, imports, etc. This is because the code itself is being imported as part of pytest instantiation, and isn't getting "covered" until the testing actually starts.
I've read pytest docs, pytest-cov and coverage docs, and tox docs, and tried several configurations, but to no avail. I've exhausted my pool of google keyword combinations that might lead me to a good solution.
Repository layout
pkg_root/
.tox/
py3/
lib/
python3.7/
site-pacakges/
plugin_module/
supporting_module.py
plugin.py
some_data.dat
plugin_module/
supporting_module.py
plugin.py
some_data.dat
tests/
conftest.py
test_my_plugin.py
tox.ini
setup.py
Some relevant snippets with commentary:
tox.ini
[pytest]
addopts = --cov={envsitepackagesdir}/plugin_module --cov-report=html
testpaths = tests
This configuration gives me an error that no data was collected; no htmlcov is created in this case.
If I just use --cov, I get (expected) very noisy coverage, which shows the functional hits and misses, but with the false misses reported above for imports, class definitions, etc.
conftest.py
pytest_plugins = ['pytester'] # Entire contents of file!
test_my_plugin.py
def test_a_thing(testdir):
testdir.makepyfile(
"""
def test_that_fixture(my_fixture):
assert my_fixture.foo == 'bar'
"""
)
result = testdir.runpytest()
result.assert_outcomes(passed=1)
How can I get an accurate report? Is there a way to defer the plugin loading until it's demanded by the pytester tests?
