@caplin/jest-image-snapshot/src/outdated-snapshot-reporter.js

Jest matcher for image comparisons. Most commonly used for visual regression testing.

/*
 * Copyright (c) 2020 American Express Travel Related Services Company, Inc.
 *
 * 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.
 */

/* eslint-disable class-methods-use-this */

const fs = require('fs');
const path = require('path');

const TOUCHED_FILE_LIST_PATH = path.join(
  process.cwd(),
  '.jest-image-snapshot-touched-files'
);

const IS_ENABLED = !!process.env.JEST_IMAGE_SNAPSHOT_TRACK_OBSOLETE;

class OutdatedSnapshotReporter {
  /* istanbul ignore next - test coverage in child process */
  static markTouchedFile(filePath) {
    if (!IS_ENABLED) return;
    const touchedListFileDescriptor = fs.openSync(TOUCHED_FILE_LIST_PATH, 'as');
    fs.writeSync(touchedListFileDescriptor, `${filePath}\n`);
    fs.closeSync(touchedListFileDescriptor);
  }

  /* istanbul ignore next - test coverage in child process */
  static readTouchedFileListFromDisk() {
    if (!fs.existsSync(TOUCHED_FILE_LIST_PATH)) return [];

    return Array.from(
      new Set(
        fs
          .readFileSync(TOUCHED_FILE_LIST_PATH, 'utf-8')
          .split('\n')
          .filter(file => file && fs.existsSync(file))
      )
    );
  }

  /* istanbul ignore next - test coverage in child process */
  onRunStart() {
    if (!IS_ENABLED) return;
    if (fs.existsSync(TOUCHED_FILE_LIST_PATH)) {
      fs.unlinkSync(TOUCHED_FILE_LIST_PATH);
    }
  }

  /* istanbul ignore next - test coverage in child process */
  onRunComplete() {
    if (!IS_ENABLED) return;
    const touchedFiles = OutdatedSnapshotReporter.readTouchedFileListFromDisk();
    const imageSnapshotDirectories = Array.from(
      new Set(touchedFiles.map(file => path.dirname(file)))
    );
    const allFiles = imageSnapshotDirectories
      .map(dir => fs.readdirSync(dir).map(file => path.join(dir, file)))
      .reduce((a, b) => a.concat(b), [])
      .filter(file => file.endsWith('-snap.png'));
    const obsoleteFiles = allFiles.filter(
      file => !touchedFiles.includes(file)
    );

    if (fs.existsSync(TOUCHED_FILE_LIST_PATH)) {
      fs.unlinkSync(TOUCHED_FILE_LIST_PATH);
    }

    obsoleteFiles.forEach((file) => {
      process.stderr.write(`Deleting outdated snapshot "${file}"...\n`);
      fs.unlinkSync(file);
    });
  }
}

module.exports = OutdatedSnapshotReporter;