firebase-js-sdk/packages/database/test/helpers/EventAccumulator.ts

/**
 * @license
 * Copyright 2017 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

export const EventAccumulatorFactory = {
  // TODO: Convert to use generics to take the most advantage of types.
  waitsForCount: maxCount => {
    // Note: This should be used sparingly as it can result in more events being raised than expected
    let count = 0;
    const condition = () => count >= maxCount;
    const ea = new EventAccumulator(condition);
    ea.onReset(() => {
      count = 0;
    });
    ea.onEvent(() => {
      count++;
    });
    return ea;
  },
  waitsForExactCount: maxCount => {
    let count = 0;
    const condition = () => {
      if (count > maxCount) {
        throw new Error('Received more events than expected');
      }
      return count === maxCount;
    };
    const ea = new EventAccumulator(condition);
    ea.onReset(() => {
      count = 0;
    });
    ea.onEvent(() => {
      count++;
    });
    return ea;
  }
};

export class EventAccumulator {
  // TODO: make these typesafe
  eventData = [];
  promise;
  resolve;
  reject;
  private onResetFxn;
  private onEventFxn;
  // eslint-disable-next-line @typescript-eslint/ban-types
  constructor(public condition: Function) {
    this.promise = new Promise((resolve, reject) => {
      this.resolve = resolve;
      this.reject = reject;
    });
  }
  addEvent(eventData?: any) {
    this.eventData = [...this.eventData, eventData];
    if (typeof this.onEventFxn === 'function') {
      this.onEventFxn();
    }
    if (this._testCondition()) {
      this.resolve(this.eventData);
    }
  }
  // eslint-disable-next-line @typescript-eslint/ban-types
  reset(condition?: Function) {
    this.eventData = [];
    this.promise = new Promise((resolve, reject) => {
      this.resolve = resolve;
      this.reject = reject;
    });
    if (typeof this.onResetFxn === 'function') {
      this.onResetFxn();
    }
    if (typeof condition === 'function') {
      this.condition = condition;
    }
  }
  // eslint-disable-next-line @typescript-eslint/ban-types
  onEvent(cb: Function) {
    this.onEventFxn = cb;
  }
  // eslint-disable-next-line @typescript-eslint/ban-types
  onReset(cb: Function) {
    this.onResetFxn = cb;
  }
  _testCondition() {
    return this.condition();
  }
}