Addons using ember-cli-typescript@4 do not get their TypeScript transpiled

[rwjblue]

We discovered this while testing a new version of ember-a11y-testing that uses ember-cli-typescript@4. During the Embroider build the .ts files (located in addon-test-support) are not transpiled into .js in Embroider's working directory.

I'm making a tracking issue here so we can work towards a solution...

[rwjblue]

/cc @chriskrycho @dfreeman (for visibility)

@scalvert - Can you share repro steps? Or plausibly make a small Embroider demo app that has the issue?

[scalvert]

Yep. Will push up a repro repo right now :)

[scalvert]

https://github.com/scalvert/a11y-embroider-repro/tree/broken

Running ember t on that branch will result in the error.

[chriskrycho]

Interesting. I believe Embroider at some point had some special handling for ember-cli-typescript, which should no longer be required – I’ll start by looking there tomorrow or Thursday if @dfreeman or @jamescdavis don’t get there first.

[dfreeman]

I'm not super familiar with the implementation details of Embroider, but at a glance this looks suspicious: https://github.com/embroider-build/embroider/blob/2842a3482119a38bed32d9fc7b8050922b46efdf/packages/compat/src/v1-addon.ts#L202:L207

Since ember-cli-typescript no longer adds any explicit plugins to the Babel config, this conditional will no longer get tripped if an addon doesn't have other plugins set up. The TS plugin (and .ts extension) are now handled within ember-cli-babel itself if ember-cli-typescript >= 4 is present or enableTypeScriptTransform is set.

[jamescdavis]

The repro doesn't have ember-a11y-testing as a dep. 😃 After adding ember-a11y-testing@4.0.0-beta.1, I was able to repro the issue. The problem has to do with detecting when an addon (but not the host app) uses ember-cli-typescript@4 and setting up Babel. I was able to get things working for the repro by tweaking things in @embroider/compat. I'll put a PR up soon.

[jamescdavis]

@dfreeman, yep that's part of it. #529 gets the repro passing, at least (I have a test package locally, but it's not building right).

[ef4]

Thanks for testing and reporting, I reviewed #529 with commentary so we can get to the bottom of this.

[scalvert]

@jamescdavis oops I forgot to add ember-a11y-testing. Can add it and push.

[scalvert]

Added.