Improved test module

[joe-pierce]

Currently we have a simple unittest suite in one file with multiple unittest classes. Better practice would be to separate each class and theme into separate files. For example the test folder would look something like this:

test/
    test_dat.py
    test_ied.py
    test_ief.py
    test_zzn.py
    test_backup.py
    test_units/
        test_section.py  # Example of testing a single unit class

We should aslo consider using the pytest package which allows for simpler test set up and provides some extra useful things like parameterisation and fixtures.

Tasks

Beta Give feedback

1. Create new test module structure
2. Refactor existing tests into new structure using pytest
3. Add some new tests with good pytest examples
4. Add documentation about how to run/write the tests
5. [Optional] Add test coverage feature to repo and widget
6. [Optional] Add GitHub Action to automate a test pipeline
7. Alter settings to prevent merge if tests are failing

[matthewjwhittle-jacobs]

Update:
I've altered the test structure, converted all tests to pytest and made a start on documentation. I have also set up a GitHub action to automatically run tests on pull requests to master and pushes on any branch. This will help us keep track if a bug gets introduced.

We should alter the repository settings to prevent merges to the main branch if tests are failling. I've added a task for this. There are some instructions here:
https://www.freecodecamp.org/news/what-are-github-actions-and-how-can-you-automate-tests-and-slack-notifications/

[matthewjwhittle-jacobs]

Code Coverage:
We can use codecov for code coverage but we would need to get the admins of the GitHub org to approve it to access private information. Might be worth discussing this with IT if we decide to go down this route. Pytest does provide tools to check code coverage (pip install pytest-cov then pytest --cov to get a report).

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