Add Sphinx integration testing

[choldgraf]

Since this is a Sphinx parser, we should add some tests that use Sphinx infrastructure to make sure it behaves as expected. As a start, something like:

• A notebook that has all of the syntax we'd expect to see from users
• A test suite that builds a site from this notebook, and checks the outputs to make sure they behave as expected (or maybe tests the AST?)

Ideally, we could set this up so that, as functionality grows, we can naturally extend the test suite. So I'd like to not do anything too bespoke and hacky.

@chrisjsewell or @mmcky or @akhmerov do you have any suggestions or template code you can contribute to start us off with a good way to test Sphinx projects?

[chrisjsewell]

Yeh, look at the test_sphinx folder (and top-level conftest.py) in the myst_parser. It does exactly this, using Sphinx’s pytest fixtures 😁

[chrisjsewell]

It also uses beautifulsoup and pytest-regressions to extract the body of HTML pages and test them against the expected outcome (some things in the footer/header can change dependent on installed package versions etc)

[choldgraf]

you are much more disciplined about writing tests than I am...

[chrisjsewell]

It’s all about that Test Driven Development life 😂

[chrisjsewell]

Most 'lower-level' testing has now been added. But we should add a full sphinx integration test (like in myst-parser)