docs: Update migration howto with jest @src alias

[arbrandes]

The migration howto was missing the @src alias in jest configuration, since it's no longer provided by the default in frontend-base.

The site.config.test.tsx circular import fix was also included.

[brian-smith-tcril]

Is there a way to have a single source of truth for asset file types? It looks like we used to just have a big list in moduleNameMapper, but now we need to call out file types in the build target too.

I don't think this is something frontend-base should maintain, each app can specify what file types are used in its assets, but needing to update that list in 2 places feels less than ideal.

[brian-smith-tcril]

Might be good to mention the build target in the example makefile is doing this for png and svg. That should make it clearer that this note is saying "if you have asset files using types that aren't covered by the example build target, you can update the build target to include those types"

[arbrandes]

@brian-smith-tcril,

Is there a way to have a single source of truth for asset file types?

I think it's just happenstance that the particular assets we want to copy over to dist are also ones that require a jestism to mock out. Another way to put it is: would you trust having the Makefile parse jest.config.js and then copy assets based on that?

I couldn't agree more with the following, though:

needing to update that list in 2 places feels less than ideal

How about we just assume what sane app authors would want to do anyway, which is to put all assets under a predictable directory name? That way the jestism remains a jestism (no way around that), but they don't have to worry about the Makefile. See changes in the latest commit.

[holaontiveros]

Haven't seen how the fail with the circular dependency works, and the solution is perfect but maybe it should be somewhere else apart from the doc so it's easily recognizable for anyone that it shouldn't like that in there.

Also maybe we need to change it in here? ->

frontend-base/shell/site.config.test.tsx

Line 11 in cb555ff

environment: EnvironmentTypes.TEST,

[arbrandes]

@holaontiveros, I don't think it's needed in the shell because the shell can't mock the entire @openedx/frontend-base for testing, like consumers can. (That type of mocking is why the workaround is needed for tests.)

[holaontiveros]

That makes sense, but then wouldn't that confuse someone that only sees that one and tries to use it as a refernce?

[arbrandes]

wouldn't that confuse someone that only sees that one and tries to use it as a refernce?

They should be using frontend-template-app@frontend-base for reference... Once we update it. :)

For now, the migration howto is the reference.