front_end/testing/UserMetricsHelpers.ts

// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import * as Host from '../core/host/host.js';

/**
 * @returns True, iff a metric event with the provided name and code was recorded. False otherwise.
 */
export function recordedMetricsContain(actionName: string, actionCode: number): boolean {
  const instance = Host.InspectorFrontendHost.InspectorFrontendHostInstance;
  if (instance instanceof Host.InspectorFrontendHost.InspectorFrontendHostStub) {
    return instance.recordedEnumeratedHistograms.some(
        event => event.actionName === actionName && event.actionCode === actionCode);
  }
  return false;
}

export function resetRecordedMetrics(): void {
  const instance = Host.InspectorFrontendHost.InspectorFrontendHostInstance;
  if (instance instanceof Host.InspectorFrontendHost.InspectorFrontendHostStub) {
    instance.recordedEnumeratedHistograms = [];
    instance.recordedPerformanceHistograms = [];
    instance.recordedCountHistograms = [];
  }
}

export function setupUserMetricHooks(): void {
  beforeEach(() => {
    const mockEnumCodes = new Map<string, Map<string, number>>();
    function getMockEnumCode(enumName: string, prop: string): number {
      if (prop === 'MAX_VALUE') {
        return 1000;
      }
      if (!mockEnumCodes.has(enumName)) {
        mockEnumCodes.set(enumName, new Map());
      }
      const propMap = mockEnumCodes.get(enumName)!;
      if (!propMap.has(prop)) {
        propMap.set(prop, propMap.size);
      }
      return propMap.get(prop)!;
    }

    // eslint-disable-next-line @typescript-eslint/naming-convention
    (globalThis as unknown as {DevToolsMetrics: unknown}).DevToolsMetrics = new Proxy({}, {
      get(_target, enumName) {
        if (typeof enumName !== 'string') {
          return undefined;
        }
        return new Proxy({}, {
          get(_target, prop) {
            if (typeof prop !== 'string' || prop === 'then') {
              return undefined;
            }
            return getMockEnumCode(enumName, prop);
          },
          has(_target, prop) {
            if (typeof prop === 'string' && /^\d+$/.test(prop)) {
              return false;
            }
            return true;
          },
          ownKeys(_target) {
            const propMap = mockEnumCodes.get(enumName);
            return propMap ? Array.from(propMap.keys()) : [];
          },
          getOwnPropertyDescriptor(_target, prop) {
            if (typeof prop !== 'string') {
              return undefined;
            }
            return {
              configurable: true,
              enumerable: true,
              value: getMockEnumCode(enumName, prop),
              writable: false,
            };
          },
        });
      },
    });
  });

  afterEach(() => {
    // eslint-disable-next-line @typescript-eslint/naming-convention
    const globalObject = globalThis as unknown as {DevToolsMetrics?: unknown};
    delete globalObject.DevToolsMetrics;
  });
}