As of the time of writing, the MediaWiki Core Jest test suite executes 48 tests in about ~20 seconds (~0.4 secs per test). Compare that to the Core QUnit test suite, which runs 797 tests in about ~4.3 seconds (~.005 secs per test). Clearly writing Jest tests the way we have been will not scale.
We should take steps to improve the speeds, while not hurting the breadth of coverage.
Related: T388059: Increase test coverage of Codex Special:Block. The coverage report by itself adds about ~5 seconds to the runtime.
Possible improvements:
- Increasing the number of workers
- Bump versions of Jest and other test utilities we use
- More aggressive mocking
- Tests of Vue components should use shallowMount instead of mount
