Add tests

[chriswales95]

Right now we're confident things are working as intended but as things grow we're going to need some tests in here. We'll want them to run in pipelines too.

[chriswales95]

This depends on localgovdrupal/localgov_elections_reporting#5 because composer needs to be able to resolve the highcharts dependencies.

[chriswales95]

When we do add the automated testing we should use https://github.com/localgovdrupal/localgov_shared_workflows

[chriswales95]

We now have tests for the new constituency provider but need more tests elsewhere too e.g. the main module and ONS plugin.

[chriswales95]

Added tests for URL aliases in #46

[finnlewis]

I see we've got some tests, nice work @chriswales95 !

I was just about to try writing some and found them.

I'll see what I can do to help extend the coverage.

[chriswales95]

Hi @finnlewis, I think we've got about 9 at the moment.

My approach has just been adding them slowly but surely. @Adnan-cds did one too.

We'll get there!

[finnlewis]

I think this might be enough to mark this done rather than hang on to it as a release blocker.