test(@angular-devkit/build-angular): add dev-server builder build inline critical CSS behavior tests

This change adds expanded unit tests for the dev-server builder's build inline critical CSS behavior using the builder test harness.

Author: clydin

packages/angular_devkit/build_angular/src/dev-server/inline-critical-css-optimization_spec.ts

@@ -0,0 +1,61 @@
+/**
+ * @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,
+  DEV_SERVER_BUILDER_INFO,
+  describeBuilder,
+  setupBrowserTarget,
+} from '../setup';
+
+describeBuilder(serveWebpackBrowser, DEV_SERVER_BUILDER_INFO, (harness) => {
+  describe('Behavior: "browser builder inline critical css"', () => {
+    beforeEach(async () => {
+      setupBrowserTarget(harness, {
+        optimization: {
+          styles: {
+            minify: true,
+            inlineCritical: true,
+          },
+        },
+        styles: ['src/styles.css'],
+      });
+
+      await harness.writeFiles({
+        'src/styles.css': 'body { color: #000 }',
+      });
+
+      // Application code is not needed for these tests
+      await harness.writeFile('src/main.ts', '');
+    });
+
+    it('inlines critical css when enabled in the "browserTarget" options', async () => {
+      harness.useTarget('serve', {
+        ...BASE_OPTIONS,
+      });
+
+      await harness
+        .execute()
+        .pipe(
+          timeout(39000),
+          mergeMap(async ({ result }) => {
+            expect(result?.success).toBeTrue();
+
+            if (result?.success) {
+              const response = await fetch(`${result.baseUrl}index.html`);
+              expect(await response.text()).toContain(`body{color:#000;}`);
+            }
+          }),
+          take(1),
+        )
+        .toPromise();
+    });
+  });
+});

packages/angular_devkit/build_angular/src/dev-server/tests/behavior/build-inline-critical-css_spec.ts

@@ -5,9 +5,14 @@
  * 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 { json } from '@angular-devkit/core';
+import { readFileSync } from 'fs';
 import { buildWebpackBrowser } from '../../browser';
 import { Schema as BrowserSchema } from '../../browser/schema';
-import { BASE_OPTIONS as BROWSER_BASE_OPTIONS } from '../../browser/tests/setup';
+import {
+  BASE_OPTIONS as BROWSER_BASE_OPTIONS,
+  BROWSER_BUILDER_INFO,
+} from '../../browser/tests/setup';
 import { BuilderHarness } from '../../testing/builder-harness';
 import { Schema } from '../schema';
 
@@ -34,12 +39,38 @@ export const BASE_OPTIONS = Object.freeze<Schema>({
  */
 export const BUILD_TIMEOUT = 15000;
 
+/**
+ * Cached browser builder option schema
+ */
+let browserSchema: json.schema.JsonSchema | undefined = undefined;
+
+/**
+ * Adds a `build` target to a builder test harness for the browser builder with the base options
+ * used by the browser builder tests.
+ *
+ * @param harness The builder harness to use when setting up the browser builder target
+ * @param extraOptions The additional options that should be used when executing the target.
+ */
 export function setupBrowserTarget<T>(
   harness: BuilderHarness<T>,
   extraOptions?: Partial<BrowserSchema>,
 ): void {
-  harness.withBuilderTarget('build', buildWebpackBrowser, {
-    ...BROWSER_BASE_OPTIONS,
-    ...extraOptions,
-  });
+  if (!browserSchema) {
+    browserSchema = JSON.parse(
+      readFileSync(BROWSER_BUILDER_INFO.schemaPath, 'utf8'),
+    ) as json.schema.JsonSchema;
+  }
+
+  harness.withBuilderTarget(
+    'build',
+    buildWebpackBrowser,
+    {
+      ...BROWSER_BASE_OPTIONS,
+      ...extraOptions,
+    },
+    {
+      builderName: BROWSER_BUILDER_INFO.name,
+      optionSchema: browserSchema,
+    },
+  );
 }