test: add cypress end-to-end test setup

[ddehart]

What:

This PR relates to #7 and replaces #27 while incorporating a lot of what @JacobMGEvans learned while working on that PR.

Why:

End-to-end tests can help combat unintentional side effects and regressions.

How:

This PR adds a single end-to-end test that verifies the app's initial rendered state. It also adds some custom commands for Cypress to abstract some of the less obvious queries needed to test Testing Playground. Finally, it adds some properties to several components, some (data-testid) purely for Cypress/Testing Library queries and others (title) that improve both testability and accessibility.

Checklist:

• Tests N/A
• Ready to be merged
  

[JacobMGEvans]

Awesome! Thanks for the credit, means a lot.

[marcosvega91]

Hi @ddehart thanks for working on this, you're very awesome 😄

I don't know if this PR is finished but I have added some comments

[marcosvega91]

Your work is awesome, last comments and for me is ready 🥳

[ddehart]

@marcosvega91 done! Thanks for the review

[marcosvega91]

fine, thanks :)

[smeijer]

Thanks all!

Especially to @JacobMGEvans for all the time and energy you put into this under #27. I should have merged that one ages ago instead of delaying it because of some minor improvements. I'm truly sorry for that to have happened.

Also thanks for @ddehart for picking up that PR, and bring it to a mergeable state again. And to @marcosvega91 for the review. Much appreciated.

[smeijer]

😱 I did it!

[smeijer]

@all-contributors please add @ddehart for test

[allcontributors]

@smeijer

I've put up a pull request to add @ddehart! 🎉

[smeijer]

@all-contributors please add @JacobMGEvans for test

[allcontributors]

@smeijer

I've put up a pull request to add @JacobMGEvans! 🎉