Add (and integrate previous) tests for Pepys Timeline

[robintw]

Pepys Timeline is currently significantly under-tested. There are a few tests in the pepys-timeline repo that should be copied over and integrated, and then we should add tests for the Flask app (for example, using pytest-flask).

The areas that need covering by tests include:

• The SQL query - this is partly covered by @arunlal-v's tests in the pepys-timeline repo. These need copying over to this repo, and then @arunlal-v can continue work on them with a PR here
• The Flask app - this will mostly be Ivan's responsibility (is he added as a collaborator to this repo?)
• The Javascript interface - I've never worked on front-end testing, but I imagine we could do something using Selenium or similar (which I have a bit of experience with, as I've used it for web scraping)

[robintw]

@arunlal-v I've created a PR to add your original test functions from pepys-timeline. See #891.

I've done some fairly minor changes to make the tests work with pytest (which we use for tests in Pepys Import), and to satisfy the automatic code formatter that we use (black) and the Python style testing tool we use (flake8).

To be able to contribute, I'd suggest:

• Cloning this repo
• Following the Developer Guide to get Python set up with all the dependencies, and try running the tests with pytest. Don't worry about running tests for everything - you may well find that some fail - but make sure you can run your own tests by running pytest tests/timeline_tests/test_dashboard_sql_functions.py
• Following these instructions to get the pre-commit hook set up, so that code formatting and checking is automatically done on each commit

You should then be able to create a new branch and PR, and work on the tests.

Thank you for developing the tests using many of the same libraries that we're using for Pepys Import testing - for example, testing.postgresql. We have a mix of different coding styles in the Pepys Import tests, but we're trying to move away from unittest-style asserts - like self.assertTrue(validate(rows, ["G"], ["12:12:12"])) or self.assertEqual(a, 42), and instead use pytest-style asserts like assert validate(rows, ["G"], ["12:12:12"]) and assert a == 42 - as they're cleaner to read, and actually give better error messages.

Let me know if you need any help with any of these steps.

@krsnik93 It'd be good if you could follow these instructions too, then we can work on the Flask/JS tests in this repo too.

[rnllv]

Thanks for the heads up @robintw. I'll go through them and continue with the sql test cases.

[rnllv]

@robintw, @IanMayo,

I've enhanced the business logic description here. Should this be split between the python test file and the actual SQL file?