src/test/perfetto_ui_test_helper.ts

// Copyright (C) 2021 The Android Open Source Project
//
// 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.

import fs from 'fs';
import net from 'net';
import path from 'path';
import pixelmatch from 'pixelmatch';
import {PNG} from 'pngjs';
import {Page} from 'puppeteer';

// These constants have been hand selected by comparing the diffs of screenshots
// between Linux on Mac. Unfortunately font-rendering is platform-specific.
// Even though we force the same antialiasing and hinting settings, some minimal
// differences exist.
const DIFF_PER_PIXEL_THRESHOLD = 0.35;
const DIFF_MAX_PIXELS = 50;

// Waits for the Perfetto UI to be quiescent, using a union of heuristics:
// - Check that the progress bar is not animating.
// - Check that the omnibox is not showing a message.
// - Check that no redraws are pending in our RAF scheduler.
// - Check that all the above is satisfied for |minIdleMs| consecutive ms.
export async function waitForPerfettoIdle(page: Page, minIdleMs?: number) {
  // eslint-disable-next-line @typescript-eslint/strict-boolean-expressions
  minIdleMs = minIdleMs || 3000;
  const tickMs = 250;
  const timeoutMs = 60000;
  const minIdleTicks = Math.ceil(minIdleMs / tickMs);
  const timeoutTicks = Math.ceil(timeoutMs / tickMs);
  let consecutiveIdleTicks = 0;
  let reasons: string[] = [];
  for (let ticks = 0; ticks < timeoutTicks; ticks++) {
    await new Promise((r) => setTimeout(r, tickMs));
    const isShowingMsg = !!(await page.$('.omnibox.message-mode'));
    const isShowingAnim = !!(await page.$('.progress.progress-anim'));
    const hasPendingRedraws = await (
      await page.evaluateHandle('raf.hasPendingRedraws')
    ).jsonValue();

    if (isShowingAnim || isShowingMsg || hasPendingRedraws) {
      consecutiveIdleTicks = 0;
      reasons = [];
      if (isShowingAnim) {
        reasons.push('showing progress animation');
      }
      if (isShowingMsg) {
        reasons.push('showing omnibox message');
      }
      if (hasPendingRedraws) {
        reasons.push('has pending redraws');
      }
      continue;
    }
    if (++consecutiveIdleTicks >= minIdleTicks) {
      return;
    }
  }
  throw new Error(
    `waitForPerfettoIdle() failed. Did not reach idle after ${timeoutMs} ms. ` +
      `Reasons not considered idle: ${reasons.join(', ')}`,
  );
}

export function getTestTracePath(fname: string): string {
  const fPath = path.join('test', 'data', fname);
  if (!fs.existsSync(fPath)) {
    throw new Error('Could not locate trace file ' + fPath);
  }
  return fPath;
}

export async function compareScreenshots(
  reportPath: string,
  actualFilename: string,
  expectedFilename: string,
) {
  if (!fs.existsSync(expectedFilename)) {
    throw new Error(
      `Could not find ${expectedFilename}. Run wih REBASELINE=1.`,
    );
  }
  const actualImg = PNG.sync.read(fs.readFileSync(actualFilename));
  const expectedImg = PNG.sync.read(fs.readFileSync(expectedFilename));
  const {width, height} = actualImg;
  expect(width).toEqual(expectedImg.width);
  expect(height).toEqual(expectedImg.height);
  const diffPng = new PNG({width, height});
  const diff = await pixelmatch(
    actualImg.data,
    expectedImg.data,
    diffPng.data,
    width,
    height,
    {
      threshold: DIFF_PER_PIXEL_THRESHOLD,
    },
  );
  if (diff > DIFF_MAX_PIXELS) {
    const diffFilename = actualFilename.replace('.png', '-diff.png');
    fs.writeFileSync(diffFilename, PNG.sync.write(diffPng));
    fs.appendFileSync(
      reportPath,
      `${path.basename(actualFilename)};${path.basename(diffFilename)}\n`,
    );
    fail(`Diff test failed on ${diffFilename}, delta: ${diff} pixels`);
  }
  return diff;
}

// If the user has a trace_processor_shell --httpd instance open, bail out,
// as that will invalidate the test loading different data.
export async function failIfTraceProcessorHttpdIsActive() {
  return new Promise<void>((resolve, reject) => {
    const client = new net.Socket();
    client.connect(9001, '127.0.0.1', () => {
      const err =
        'trace_processor_shell --httpd detected on port 9001. ' +
        'Bailing out as it interferes with the tests. ' +
        'Please kill that and run the test again.';
      console.error(err);
      client.destroy();
      reject(err);
    });
    client.on('error', (e: {code: string}) => {
      expect(e.code).toBe('ECONNREFUSED');
      resolve();
    });
    client.end();
  });
}