test: use random port for e2e express http server tests

Author: jbedard

tests/legacy-cli/e2e/tests/i18n/ivy-localize-basehref.ts

@@ -59,13 +59,17 @@ export default async function () {
     await ng('e2e', `--configuration=${lang}`, '--port=0');
 
     // Execute Application E2E tests for a production build without dev server
-    const server = externalServer(outputPath, (baseHrefs[lang] as string) || '/');
+    const { server, port, url } = await externalServer(
+      outputPath,
+      (baseHrefs[lang] as string) || '/',
+    );
     try {
       await ng(
         'e2e',
+        `--port=${port}`,
         `--configuration=${lang}`,
         '--dev-server-target=',
-        `--base-url=http://localhost:4200${baseHrefs[lang] || '/'}`,
+        `--base-url=${url}`,
       );
     } finally {
       server.close();
@@ -89,13 +93,17 @@ export default async function () {
     await ng('e2e', `--configuration=${lang}`, '--port=0');
 
     // Execute Application E2E tests for a production build without dev server
-    const server = externalServer(outputPath, '/test' + (baseHrefs[lang] || '/'));
+    const { server, port, url } = await externalServer(
+      outputPath,
+      '/test' + (baseHrefs[lang] || '/'),
+    );
     try {
       await ng(
         'e2e',
+        `--port=${port}`,
         `--configuration=${lang}`,
         '--dev-server-target=',
-        `--base-url=http://localhost:4200/test${baseHrefs[lang] || '/'}`,
+        `--base-url=${url}`,
       );
     } finally {
       server.close();

tests/legacy-cli/e2e/tests/i18n/ivy-localize-es2015.ts

@@ -40,13 +40,14 @@ export default async function () {
     await ng('e2e', `--configuration=${lang}`, '--port=0');
 
     // Execute Application E2E tests for a production build without dev server
-    const server = externalServer(outputPath, `/${lang}/`);
+    const { server, port, url } = await externalServer(outputPath, `/${lang}/`);
     try {
       await ng(
         'e2e',
+        `--port=${port}`,
         `--configuration=${lang}`,
         '--dev-server-target=',
-        `--base-url=http://localhost:4200/${lang}/`,
+        `--base-url=${url}`,
       );
     } finally {
       server.close();

tests/legacy-cli/e2e/tests/i18n/ivy-localize-es5.ts

@@ -44,13 +44,14 @@ export default async function () {
     await ng('e2e', `--configuration=${lang}`, '--port=0');
 
     // Execute Application E2E tests for a production build without dev server
-    const server = externalServer(outputPath, `/${lang}/`);
+    const { server, port, url } = await externalServer(outputPath, `/${lang}/`);
     try {
       await ng(
         'e2e',
+        `--port=${port}`,
         `--configuration=${lang}`,
         '--dev-server-target=',
-        `--base-url=http://localhost:4200/${lang}/`,
+        `--base-url=${url}`,
       );
     } finally {
       server.close();

tests/legacy-cli/e2e/tests/i18n/ivy-localize-locale-data-augment.ts

@@ -43,13 +43,14 @@ export default async function () {
     await ng('e2e', `--configuration=${lang}`, '--port=0');
 
     // Execute Application E2E tests for a production build without dev server
-    const server = externalServer(outputPath, `/${lang}/`);
+    const { server, port, url } = await externalServer(outputPath, `/${lang}/`);
     try {
       await ng(
         'e2e',
+        `--port=${port}`,
         `--configuration=${lang}`,
         '--dev-server-target=',
-        `--base-url=http://localhost:4200/${lang}/`,
+        `--base-url=${url}`,
       );
     } finally {
       server.close();

tests/legacy-cli/e2e/tests/i18n/ivy-localize-server.ts

@@ -2,6 +2,7 @@ import express from 'express';
 import { join } from 'path';
 import { getGlobalVariable } from '../../utils/env';
 import { appendToFile, expectFileToMatch, writeFile } from '../../utils/fs';
+import { findFreePort } from '../../utils/network';
 import { installWorkspacePackages } from '../../utils/packages';
 import { ng } from '../../utils/process';
 import { updateJsonFile } from '../../utils/project';
@@ -13,6 +14,7 @@ const snapshots = require('../../ng-snapshot/package.json');
 export default async function () {
   // TODO: Re-enable pending further Ivy/Universal/i18n work
   return;
+  const port = await findFreePort();
 
   // Setup i18n tests and config.
   await setupI18nConfig();
@@ -113,10 +115,10 @@ export default async function () {
     const { i18nApp } = (await import(serverBundle)) as {
       i18nApp(locale: string): express.Express;
     };
-    const server = i18nApp(lang).listen(4200, 'localhost');
+    const server = i18nApp(lang).listen(port, 'localhost');
     try {
       // Execute without a devserver.
-      await ng('e2e', `--configuration=${lang}`, '--dev-server-target=');
+      await ng('e2e', `--port=${port}`, `--configuration=${lang}`, '--dev-server-target=');
     } finally {
       server.close();
     }

tests/legacy-cli/e2e/tests/i18n/ivy-localize-serviceworker.ts

@@ -8,11 +8,13 @@ import {
   replaceInFile,
   writeFile,
 } from '../../utils/fs';
+import { findFreePort } from '../../utils/network';
 import { installPackage } from '../../utils/packages';
 import { ng } from '../../utils/process';
 import { updateJsonFile } from '../../utils/project';
 import { expectToFail } from '../../utils/utils';
 import { readNgVersion } from '../../utils/version';
+import { externalServer } from './setup';
 
 export default async function () {
   // TEMP: disable pending i18n updates
@@ -154,9 +156,7 @@ export default async function () {
     await expectFileToExist(`${baseDir}/${lang}/ngsw.json`);
 
     // Ivy i18n doesn't yet work with `ng serve` so we must use a separate server.
-    const app = express();
-    app.use(express.static(resolve(baseDir, lang)));
-    const server = app.listen(4200, 'localhost');
+    const { server, port } = await externalServer(resolve(baseDir, lang));
     try {
       // Add E2E test for locale
       await writeFile(
@@ -180,7 +180,7 @@ export default async function () {
       );
 
       // Execute without a devserver.
-      await ng('e2e', '--dev-server-target=');
+      await ng('e2e', '--dev-server-target=', `--port=${port}`);
     } finally {
       server.close();
     }

tests/legacy-cli/e2e/tests/i18n/setup.ts

@@ -9,11 +9,13 @@ import {
   replaceInFile,
   writeFile,
 } from '../../utils/fs';
+import { findFreePort } from '../../utils/network';
 import { installPackage } from '../../utils/packages';
 import { ng } from '../../utils/process';
 import { updateJsonFile } from '../../utils/project';
-import { expectToFail } from '../../utils/utils';
 import { readNgVersion } from '../../utils/version';
+import { Server } from 'http';
+import { AddressInfo } from 'net';
 
 // Configurations for each locale.
 export const baseDir = 'dist/test-project';
@@ -67,13 +69,33 @@ export const langTranslations = [
 ];
 export const sourceLocale = langTranslations[0].lang;
 
-export const externalServer = (outputPath: string, baseUrl = '/') => {
+export interface ExternalServer {
+  readonly server: Server;
+  readonly port: number;
+  readonly url: string;
+}
+
+/**
+ * Create an `express` `http.Server` listening on a random port.
+ *
+ * Call .close() on the server return value to close the server.
+ */
+export async function externalServer(outputPath: string, baseUrl = '/'): Promise<ExternalServer> {
   const app = express();
   app.use(baseUrl, express.static(resolve(outputPath)));
 
-  // call .close() on the return value to close the server.
-  return app.listen(4200, 'localhost');
-};
+  return new Promise((resolve) => {
+    const server = app.listen(0, 'localhost', () => {
+      const { port } = server.address() as AddressInfo;
+
+      resolve({
+        server,
+        port,
+        url: `http://localhost:${port}${baseUrl}`,
+      });
+    });
+  });
+}
 
 export const formats = {
   'xlf': {