Method fn

lib/internal/test_runner/mock/mock.js:439–460

* Creates a mock function tracker. * @param {Function} [original] - The original function to be tracked. * @param {Function} [implementation] - An optional replacement function for the original one. * @param {object} [options] - Additional tracking options. * @param {number} [options.tim

(
    original = function() {},
    implementation = original,
    options = kEmptyObject,
  )

   * @returns {ProxyConstructor} The mock function tracker.
   */
  fn(
    original = function() {},
    implementation = original,
    options = kEmptyObject,
  ) {
    if (original !== null && typeof original === 'object') {
      options = original;
      original = function() {};
      implementation = original;
    } else if (implementation !== null && typeof implementation === 'object') {
      options = implementation;
      implementation = original;
    }

    validateFunction(original, 'original');
    validateFunction(implementation, 'implementation');
    validateObject(options, 'options');
    const { times = Infinity } = options;
    validateTimes(times, 'options.times');
    const ctx = new MockFunctionContext(implementation, { __proto__: null, original }, times);
    return this.#setupMock(ctx, original);
  }

  /**
   * Creates a method tracker for a specified object or function.