Update dependency tracking after modules are loaded from AVA's "require" configuration

[lo1tuma]

See next steps at #2049 (comment).

Original issue description follows.

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According to the watch-mode documentation dependency tracking should work when custom extensions/transpilers are configured directly in ava.config.js or in the package.json. The linked documentation (06-configuration.md) doesn’t really explain how this should be done. In the babel recipe however it is explained how to utilize babel transpiling for source files, the recommendation is to use the require option to load e.g. @babel/register. The problem with that is, that dependency tracking is installed before the require option is executed.

I followed the instructions in the babel recipe to transpile typescript source files with @babel/register and @babel/preset-typescript via the ava require option. Since the dependency tracking is installed before this step, it is unaware of the additional file extensions like ts and tsx that @babel/register adds.

I’m a little bit confused right now, because the documentation says it should work somehow, but it doesn’t explain how.

[fotonmoton]

You can check out this issue, I have same frustration. Here working repo with TypeScript support for AVA.

[novemberborn]

Nice find @lo1tuma!

You're right, the dependency tracker works by decorating the functions in require.extensions. Thus, it misses any additional functions added when AVA loads the modules from its require configuration.

What we should do is after each module is loaded, go through require.extensions again to decorate any now undecorated functions. That way we can track most of the dependencies.

[novemberborn]

See these lines which installs the tracker for the first time:

https://github.com/avajs/ava/blob/334e15b4af06492c9aed2800a0764f245d6a908b/lib/worker/subprocess.js#L104:L107

Note that the comment applies to precompilerHook.install().

Then, the module is loaded here:

ava/lib/worker/subprocess.js

Line 111 in 334e15b

const required = require(mod);