Refactor tests

[dstansby]

This makes the tests a bit easier to extend by:

• Defining a helper function fixture to generate a package from a given set of configuration options (in tests/helpers.py conftest.py)
• Defining the configuration within the tests that are being used, instead of in conftest.py. This makes it easier to see what config each test is using next to the actual test.

[samcunliffe]

Ah. The conflicts are from me in

• 412

(Soz)

[dstansby]

Thanks for comments! I won't have time to fix this in the next couple of weeks, so someone else feel free to take over if you're keen to get this in quicker!

[samcunliffe]

---

At the moment the approach of making the tests directory a package by adding an __init__.py (presumably so we can use a relative import for helpers module) seems to break the ability to run tests directly by running pytest or pytest -s from the root of the repository (with the latter being what we currently recommend in the developer notes in the README), though tests do still run fine using tox. Specifically I get the following errors on test collection

_______________________________________ ERROR collecting tests/test_git_init.py ________________________________________
ImportError while importing test module '.../python-tooling/tests/test_git_init.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
tests/test_git_init.py:8: in <module>
    from .helpers import gen_package
E   ModuleNotFoundError: No module named 'tests'
______________________________________ ERROR collecting tests/test_package_gen.py ______________________________________
ImportError while importing test module '.../python-tooling/tests/test_package_gen.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
tests/test_package_gen.py:6: in <module>
    from .helpers import gen_package
E   ModuleNotFoundError: No module named 'tests'

I guess this is because the tests package is not being added to the Python path by pytest and so the relative import doesn't work?

I think we can avoid having tests be a package by either wrapping the gen_package function into a fixture in conftest.py

import pytest

def _gen_package(
    path: pathlib.Path, project_config: dict[str, str]
) -> subprocess.CompletedProcess[str]:
    ...

@pytest.fixture
def gen_package():
    return _gen_package

and having the tests which use it accept a gen_package argument [...]

I went for your first suggestion. Adding fixtures as defaults to functions returned by fixtures ended up a bit messy. This way is explicit-er and only repeats one line in the two tests... so not too terrible?