Improve watcher

[lydell]

This makes the watcher faster and more stable! As a bonus, this made the code much more organized.

• Concentrate all process.exit in elm-test.js (except one in Install.js where I found no clean solution). Besides making the code easier to follow, it allows the watcher to continue running (and recover) even if there are errors.

• Don’t crash/stop running tests if files are removed.

• Pick up new Elm files added.

• Fixes Watcher: Cancel previous compilation and test runs #225

  We already had code for waiting for the previous run to finish before starting the next run, but it queued up every single file change/add/remove event and ran that many runs one after the other. Now, for all watch events during a run we run once after the current run for all of them. We also sleep 100 ms at the start of each run to catch more events happening close by (such as when adding/removing a whole folder of tests). (Note: We used to sleep at least 500 ms via the awaitWriteFinish chokidar option.)

  I’ve also tested manually that running elm-format on save doesn’t cause double test runs: Cancel previous running compile process in watch mode #194

• Fixes Error if run from a subdirectory #355

  We now find the closest elm.json upwards in the folder hierarchy.

• Resolves Fix watch for packages when there are compilation errors in src/ #453 (comment)

  The watcher now listens for changes to elm.json and properly recalculates things. I thought that I would have to recalculate some things only when elm.json changes for performance, but after making the globbing faster there was no need so we simply rebuild everything on each run.

• Closes Replace new Promise and .then with async/await #463 and closes Moving to async/await: lib/Runner.js #464

  I can’t find any more places to use async/await.

• elm.json is now decoded properly in one place rather than here and there and just being any. We now have 0 explicit any type annotations!

• elm-test.js now only contains CLI logic and subcommand dispatching. The code for running tests have been moved to RunTests.js and to FindTests.js (which used to be called Runner.js).

• Improved .flowconfig that is stricter. Closes Ban the flow any type. #478

• And lots of little code improvements along the way! I only touched things that I needed to change anyway in order to not make the diff balloon too much.

I’ve done some manual testing on Windows, Mac and Linux to make sure things work like they should.

[harrysarson]

Thanks for the comments explaining the rearrangements; they are really helpful. I am getting there:

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Thanks @pipefail too for your help, much appreciated :)

[harrysarson]

Just got runTests to go. Nearly there 🎉

[harrysarson]

Happy!

[harrysarson]

I like the queuing a lot and thanks for the help finding which code had moved where. You ready for me to merge?

[lydell]

I’m ready!