Draft: add some basic testing
Add some basic testing support as outlined in #2. Tests are run for all Python versions supported by all current supported Django versions.
The tests themselves are in tests/test_migration.py and simply test:
- Default behaviour is to be disabled
- If enabled, the basic snapshot behaviour is as expected
- If an error is returned, an exception is raised
This MR does not test overrides based on settings values, the aim of this MR is more to get some compatibility smoke-testing in place so that we can know early if we break on what should be a supported Python/Django combination.
Most of this MR is plumbing to get to this stage and is broken out into separate commits. The majority of this work is copying the test harness code from the webapp boilerplate along with flake8, black, isort, gitignore and editorconfig configuration.
The tox and CI configuration is lightly modified from the webapp boilerplate with the addition of Django version as an extra testing axis.
Closes #2