test: add size checks to prod build e2e tests

tests/legacy-cli/e2e/tests/build/prod-build.ts

@@ -1,11 +1,30 @@
-import { readdirSync } from 'fs';
+import { statSync } from 'fs';
 import { join } from 'path';
 import { getGlobalVariable } from '../../utils/env';
-import { expectFileToExist, expectFileToMatch } from '../../utils/fs';
+import { expectFileToExist, expectFileToMatch, readFile } from '../../utils/fs';
 import { expectGitToBeClean } from '../../utils/git';
 import { ng } from '../../utils/process';
 
 
+function verifySize(bundle: string, baselineBytes: number) {
+  const size = statSync(`dist/test-project/${bundle}`).size;
+  const percentageBaseline = baselineBytes * 10 / 100;
+  const maxSize = baselineBytes + percentageBaseline;
+  const minSize = baselineBytes - percentageBaseline;
+
+  if (size >= maxSize) {
+    throw new Error(
+      `Expected ${bundle} size to be less than ${maxSize / 1024}Kb but it was ${size / 1024}Kb.`,
+    );
+  }
+
+  if (size <= minSize) {
+    throw new Error(
+      `Expected ${bundle} size to be greater than ${minSize / 1024}Kb but it was ${size / 1024}Kb.`,
+    );
+  }
+}
+
 export default async function () {
   // TODO(architect): Delete this test. It is now in devkit/build-angular.
 
@@ -25,12 +44,22 @@ export default async function () {
   await expectFileToMatch('dist/test-project/index.html', /styles\.[0-9a-f]{20}\.css/);
   await expectFileToMatch('dist/test-project/3rdpartylicenses.txt', /MIT/);
 
-  const dirContents = readdirSync('./dist/test-project');
-  const mainES5 = dirContents.find(name => /main-es5.[a-z0-9]+\.js/.test(name));
-  await expectFileToMatch(`dist/test-project/${mainES5}`, bootstrapRegExp);
+  const indexContent = await readFile('dist/test-project/index.html');
+  const mainES5Path = indexContent.match(/src="(main-es5\.[a-z0-9]{0,32}\.js)"/)[1];
+  const mainES2015Path = indexContent.match(/src="(main-es2015\.[a-z0-9]{0,32}\.js)"/)[1];
+
+  // Content checks
+  await expectFileToMatch(`dist/test-project/${mainES5Path}`, bootstrapRegExp);
+  await expectFileToMatch(`dist/test-project/${mainES2015Path}`, bootstrapRegExp);
 
-  const mainES2015 = dirContents.find(name => /main-es2015.[a-z0-9]+\.js/.test(name));
-  await expectFileToMatch(`dist/test-project/${mainES2015}`, bootstrapRegExp);
+  // Size checks in bytes
+  if (ivyProject) {
+    verifySize(mainES5Path, 147789);
+    verifySize(mainES2015Path, 130153);
+  } else {
+    verifySize(mainES5Path, 155523);
+    verifySize(mainES2015Path, 135394);
+  }
 
   // Check that the process didn't change local files.
   await expectGitToBeClean();