Address follow-up work for #14639

[philipp-spiess]

This PR adds a few more test cases to #14639 and updates the documentation.

[adamwathan]

Do we specifically check for typography or do we bail on any complex object under theme?

[philipp-spiess]

This bails out right now because it's using a function inside theme.

[adamwathan]

Got it so should that be how the test is named then since it's not really about typography stuff? It's just testing another heuristic right.

[adamwathan]

Also do we have a heuristic that prevents deeply nested objects as theme values?

[philipp-spiess]

Also do we have a heuristic that prevents deeply nested objects as theme values?

I don't think we do, but this is what this should eventually be, I think. I think in the compat layer right now these typography values would be added to the Theme, I did not see any heuristic trying to remove it.

We'll need to be able to support functions in the theme object and when we do we have to figure out how to still not add stuff for typography. That's really the two differences here.

Right now that test is not different from the one above "does not upgrade JS config files with functions in the theme config", so we can drop it. I just wanted to be explicit about this case since when we add support for the one above, we probably don't want to forget that this should not do weirdly nested stuff now.

[RobinMalfait]

Since this PR isn't merged yet, one thing I noticed is that if you use the default config most people have (from https://tailwindcss.com/docs/installation), that looks something like:

/** @type {import('tailwindcss').Config} */
module.exports = {
  content: ["./src/**/*.{html,js}"],
  theme: {
    extend: {},
  },
  plugins: [],
}

Then we inject a @theme that is empty:

@import "tailwindcss";

@source "./**/*.{html,js}";

@theme {}

In this case we can prevent injecting the @theme.

[philipp-spiess]

@thecrypticace Thanks for the added heuristics! I have updated the tests a bit so they now go off real world data we want to cover (the typography extension use case) but the heuristics is still sound 👍

[thecrypticace]

seems good to me now — probably want to get @adamwathan to take a look before merging