Changes to testing

[zachberry]

Currently Obojobo has 100% test coverage, which is great but does slow down development of new ideas. Additionally 100% code coverage doesn't guarantee a 100% working product. This is just a general note of things for us to consider with testing the project in the future:

• Mutation testing - https://stryker-mutator.io/docs/ - This would essentially test our tests. My understanding: It would modify our code (for example turning score > 100 to score <= 100) and make sure that related tests fail. If tests don't fail then it exposes a poorly written test, as related tests should fail when the code was mutated.
• Property testing - https://dev.to/tobiastimm/property-based-testing-with-react-and-fast-check-3dce - Test for edge cases by forcing inputs for cases we aren't planning for and making sure tests still pass. This theoretically covers the type of bugs users might experience in production and doesn't require us to think of an exhaustive list of inputs.
• Focus on testing the UI of a component instead of its underlying parts - https://kentcdodds.com/blog/testing-implementation-details - This may allow us to drop 100% coverage as we don't need to exhaustively test the underlying pieces of a component, we just need to make sure the end-user experience works for all states of a component. However this would be impossible to automatically enforce.

[zachberry]

Another idea - implement a code coverage bot like on the Katex project. Example: KaTeX/KaTeX#2183

This provides a delta of the change in code coverage for a PR

[zachberry]

Here's a jest project like codecov mentioned above - https://github.com/marketplace/actions/jest-coverage-report