Jest was in the plugin array of the ESLint configuration, but no rules
were enabled. So ESLint hasn't checked any Jest rules yet.
So I activated the recommended Jest rules and added a few more. Then I
fixed the issues (mostly automatically). I have deactivated the rules
"jest/expect-expect" and "jest/no-done-callback" for the time being, as
they would have entailed major changes. I didn't want to make the PR too
big.
I'm not a Jest expert, but the changes so far look good to me. What do
you think of that @khassel? 🙂
When trying to debug why the tests broke for
https://github.com/MichMich/MagicMirror/pull/2946 I found that the tests
does not wait for the app to start and close. So if the startup isn't
blocking that would fail.
So I added a callback for `close()` too and converted them to promises
for the `startApplication()` and `stopApplication()` and updated all the
e2e tests to await both. Will try to refactor all these callbacks to
promises in a later PR.
