discourse/frontend/discourse/lib/with-side-watch.js

// From https://github.com/cardstack/boxel/blob/d54f834f/packages/host/lib/with-side-watch.js (MIT license)

const mergeTrees = require("broccoli-merge-trees");
const { WatchedDir } = require("broccoli-source");
const Plugin = require("broccoli-plugin");

class BroccoliNoOp extends Plugin {
  constructor(path) {
    super([new WatchedDir(path)]);
  }

  build() {}
}

/*
  Doesn't change your actualTree, but causes a rebuild when any of opts.watching
  trees change.

  This is helpful when your build pipeline doesn't naturally watch some
  dependencies that you're actively developing. For example, right now
  @embroider/webpack doesn't rebuild itself when non-ember libraries change.
*/
module.exports = function withSideWatch(actualTree, opts) {
  return mergeTrees([
    actualTree,
    ...opts.watching.map((w) => new BroccoliNoOp(w)),
  ]);
};