text: #!/usr/bin/env node
  // Copyright 2019 Google LLC. All Rights Reserved.
  //
  // 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.
  // =============================================================================
  
  const shell = require('shelljs');
  const {exec} = require('./test-util');
  
  function getFileSizeBytes(filename) {
    const gzipFilename = `${filename}.gzip}`;
    exec(`gzip -c ${filename} > ${gzipFilename}`, {silent: true});
    const fileSizeBytes =
        +(exec(`ls -l ${filename} | awk '{print $5}'`, {silent: true}));
    const gzipFileSizeBytes =
        +(exec(`ls -l ${gzipFilename} | awk '{print $5}'`, {silent: true}));
    return {fileSizeBytes, gzipFileSizeBytes};
  }
  
  // Get the bundle sizes from this change.
  exec(`yarn rollup -c`, {silent: true});
  const size = getFileSizeBytes('dist/tf-core.js');
  const minSize = getFileSizeBytes('dist/tf-core.min.js');
  const esmSize = getFileSizeBytes('dist/tf-core.esm.js');
  
  // Clone master and get the bundle size from master.
  const dirName = '/tmp/tfjs-core-bundle';
  exec(
      `git clone --depth=1 --single-branch ` +
          `https://github.com/tensorflow/tfjs-core.git ${dirName}`,
      {silent: true});
  
  shell.cd(dirName);
  exec(`yarn && yarn rollup -c`, {silent: true});
  
  const masterSize = getFileSizeBytes('dist/tf-core.js');
  const masterMinSize = getFileSizeBytes('dist/tf-core.min.js');
  const masterEsmSize = getFileSizeBytes('dist/tf-core.esm.js');
  
  function showDiff(newSize, masterSize) {
    const diffBytes = newSize - masterSize;
    const diffPercent = (100 * diffBytes / masterSize).toFixed(2);
    const sign = diffBytes > 0 ? '+' : '';
  
    const charWidth = 7;
    const diffKiloBytes =
        (sign + (diffBytes / 1024).toFixed(2)).padStart(charWidth, ' ');
    const masterKiloBytes =
        ((masterSize / 1024).toFixed(2)).padStart(charWidth, ' ');
    const newKiloBytes = ((newSize / 1024).toFixed(2)).padStart(charWidth, ' ');
  
    console.log(`  diff:   ${diffKiloBytes} K  (${sign}${diffPercent}%)`);
    console.log(`  master: ${masterKiloBytes} K`);
    console.log(`  change: ${newKiloBytes} K`);
  }
  
  console.log(`~~~~minified bundle~~~~`);
  console.log(`==> post-gzip`)
  showDiff(minSize.gzipFileSizeBytes, masterMinSize.gzipFileSizeBytes);
  console.log();
  console.log(`==> pre-gzip`)
  showDiff(minSize.fileSizeBytes, masterMinSize.fileSizeBytes);
  console.log();
  console.log();
  
  console.log(`~~~~unminified bundle~~~~`);
  console.log(`==> post-gzip`)
  showDiff(size.gzipFileSizeBytes, masterSize.gzipFileSizeBytes);
  console.log();
  console.log(`==> pre-gzip`)
  showDiff(size.fileSizeBytes, masterSize.fileSizeBytes);
  console.log();
  console.log();
  
  console.log(`~~~~esm bundle~~~~`);
  console.log(`==> post-gzip`)
  showDiff(esmSize.gzipFileSizeBytes, masterEsmSize.gzipFileSizeBytes);
  console.log();
  console.log(`==> pre-gzip`)
  showDiff(esmSize.fileSizeBytes, masterEsmSize.fileSizeBytes);
  console.log();
  
  exec(`rm -r ${dirName}`);
  