test(@angular-devkit/build-angular): add dev-server builder allowedHosts option tests

This change adds expanded unit tests for the dev-server builder's `allowedHosts` option using the builder test harness.

Author: clydin

packages/angular_devkit/build_angular/src/dev-server/allowed-hosts_spec.ts

@@ -0,0 +1,98 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+import fetch from 'node-fetch'; // tslint:disable-line:no-implicit-dependencies
+import { mergeMap, take, timeout } from 'rxjs/operators';
+import { serveWebpackBrowser } from '../../index';
+import {
+  BASE_OPTIONS,
+  BUILD_TIMEOUT,
+  DEV_SERVER_BUILDER_INFO,
+  describeBuilder,
+  setupBrowserTarget,
+} from '../setup';
+
+const FETCH_HEADERS = Object.freeze({ host: 'example.com' });
+
+describeBuilder(serveWebpackBrowser, DEV_SERVER_BUILDER_INFO, (harness) => {
+  describe('option: "allowedHosts"', () => {
+    beforeEach(async () => {
+      setupBrowserTarget(harness);
+
+      // Application code is not needed for these tests
+      await harness.writeFile('src/main.ts', '');
+    });
+
+    it('does not allow an invalid host when option is not present', async () => {
+      harness.useTarget('serve', {
+        ...BASE_OPTIONS,
+      });
+
+      await harness
+        .execute()
+        .pipe(
+          timeout(BUILD_TIMEOUT),
+          mergeMap(async ({ result }) => {
+            expect(result?.success).toBeTrue();
+
+            if (result?.success) {
+              const response = await fetch(`${result.baseUrl}`, { headers: FETCH_HEADERS });
+              expect(await response.text()).toBe('Invalid Host header');
+            }
+          }),
+          take(1),
+        )
+        .toPromise();
+    });
+
+    it('does not allow an invalid host when option is an empty array', async () => {
+      harness.useTarget('serve', {
+        ...BASE_OPTIONS,
+        allowedHosts: [],
+      });
+
+      await harness
+        .execute()
+        .pipe(
+          timeout(BUILD_TIMEOUT),
+          mergeMap(async ({ result }) => {
+            expect(result?.success).toBeTrue();
+
+            if (result?.success) {
+              const response = await fetch(`${result.baseUrl}`, { headers: FETCH_HEADERS });
+              expect(await response.text()).toBe('Invalid Host header');
+            }
+          }),
+          take(1),
+        )
+        .toPromise();
+    });
+
+    it('allows a host when specified in the option', async () => {
+      harness.useTarget('serve', {
+        ...BASE_OPTIONS,
+        allowedHosts: ['example.com'],
+      });
+
+      await harness
+        .execute()
+        .pipe(
+          timeout(BUILD_TIMEOUT),
+          mergeMap(async ({ result }) => {
+            expect(result?.success).toBeTrue();
+
+            if (result?.success) {
+              const response = await fetch(`${result.baseUrl}`, { headers: FETCH_HEADERS });
+              expect(await response.text()).toContain('<title>');
+            }
+          }),
+          take(1),
+        )
+        .toPromise();
+    });
+  });
+});