Allow for more flexible addon-dev appReexports

[krasnoukhov]

While appReexports is pretty great at what it's doing it's not very flexible when you don't just export { default }. For example, if you have an initializer in v2 addon and you want to make it available to app without any additional config. But initializers require initialize function to be exported too. In our case some modules need to have export * as well.

This change creates a way to have support for such scenarios:

• addon.appReexports can be called multiple times in the rollup config (we reset app-js initially when addon instance is created so there's no leftover stuff in there)
• Optionally, for a specific glob, defaultExport can be also passed in which can be set to * or { default, initialize }

Tests were adjusted to account for all this. Let me know how this looks, any guidance will be appreciated. Cheers

[ef4]

Thanks, I hadn't noticed that initializers need this, but I see you are correct.

(It's arguably a mistake that initializers ever worked this way, given how everything else in the traditional system works, but that ship has sailed and this is a feature for achieving compatibility, so I agree we should support it.)

My suggestion for how to address the concerns I've pointed out here is an API like:

function appReexports(opts: {
  from: string;
  to: string;
  include: string[];
  mapFilename?: (filename: string) => string;
+ exports?: (filename: string) => string[] | undefined;
}) {}

Returning undefined from exports would be treated the same as returning ['default'].

A usage for initializers would look like:

addon.appReexports(['**/*.js'], {
  exports(filename) {
    if (/\/initializers\//.test(filename)) {
       return ['default', 'initialize'];
    }
  }
})

[krasnoukhov]

Thanks @ef4, good feedback, everything is addressed. One note: I changed function signature to string[] | string | undefined in order to also allow export * syntax. This is also covered by the test. I hope this is not a problem, but let me know. Cheers

[krasnoukhov]

@ef4 Any other feedback here?