Allow custom postcss.config.js

[ahmeij]

Allows loading a custom postcss.config.js if it exists in the config folder.

This allows for instance enabling nesting like so:

module.exports = {
  plugins: {
    'postcss-import': {},
    'tailwindcss/nesting': {},
    tailwindcss: {},
    autoprefixer: {},
  },
}

[ahmeij]

Sorry, this looks like a duplicate of #222, although the approach is a bit different. Please let me know if this is a viable change, I can add documentation if requested.

[ahmeij]

Added test coverage and updated README as was requested in the other PR.

[flavorjones]

@ahmeij Thank you for opening this up! It looks good, and I appreciate the test and the documentation.

I made a small change to how the command is assembled, but if this goes green I think we should merge it.

[ahmeij]

Great, thanks for the fixes and merging this change @flavorjones

[muriloime]

nice work @ahmeij ! Is there a way to run it both ways (i.e. with and without postcss) in the same app? I had opened https://github.com/rails/tailwindcss-rails/pull/222 because I need two css builds ( one for emails, without css variables, and another standard tailwindcss one). I was wondering if I can migrate to this cleaner version

many thanks

[ahmeij]

@muriloime the filenames can be made configurable, they are currently all hardcoded.

I'd suggest a change like this, which would enable running the rake tasks multiple times for multiple files to generate.

      def compile_command(debug: false, input_path: "app/assets/stylesheets/application.tailwind.css", output_path: "app/assets/builds/tailwind.css", config_path: "config/tailwind.config.js", postcss_config_path: "config/postcss.config.js", **kwargs)
        command = [
          executable(**kwargs),
          "-i", Rails.root.join(input_path).to_s,
          "-o", Rails.root.join(output_path).to_s,
          "-c", Rails.root.join(config_path).to_s,
        ]

        command << "--minify" unless (debug || rails_css_compressor?)

        postcss_path = Rails.root.join(postcss_config_path)

However I don't know if this is the direction @flavorjones wants to go with this. If this is ok I can make a PR like this with some tests. I would need to know how to handle the way to long list of kwargs, I think I like the following better:

      def compile_command(debug: false, input_path: nil, output_path: nil, config_path: nil, postcss_config_path: nil, **kwargs)
        command = [
          executable(**kwargs),
          "-i", Rails.root.join(input_path || "app/assets/stylesheets/application.tailwind.css").to_s,
          "-o", Rails.root.join(output_path || "app/assets/builds/tailwind.css").to_s,
          "-c", Rails.root.join(config_path || "config/tailwind.config.js").to_s,
        ]

        command << "--minify" unless (debug || rails_css_compressor?)

        postcss_path = Rails.root.join(postcss_config_path || "config/postcss.config.js")