cli-testing-library/src/mutation-observer.ts

Simple and complete CLI testing utilities that encourage good testing practices.

// Used for `MutationObserver`. Unsure if it's really needed, but it's worth mentioning that these are not tied to
// specific CLI instances of `render`. This means that if there are e2e CLI tests that run in parallel, they will
// execute far more frequently than needed.
const _observers = new Map();

// Not perfect as a way to make "MutationObserver" unique IDs, but it should work
let mutId = 0;

class MutationObserver {
  _cb: () => void;
  _id: number;

  constructor(cb: () => void) {
    this._id = ++mutId;
    this._cb = cb;
  }

  observe() {
    _observers.set(this._id, this._cb);
  }

  disconnect() {
    _observers.delete(this._id);
  }
}

function _runObservers() {
  Array.from(_observers.values()).forEach((cb) => cb());
}

export { _runObservers, MutationObserver };