test(@angular/build): add dev-server HMR enabled console message tests

Tests of the development server's console message output for the `hmr`
option including enabled, disabled, and default cases.

packages/angular/build/src/builders/dev-server/tests/options/hmr_spec.ts

@@ -0,0 +1,83 @@
+/**
+ * @license
+ * Copyright Google LLC 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.dev/license
+ */
+
+import { logging } from '@angular-devkit/core';
+import { executeDevServer } from '../../index';
+import { executeOnceAndFetch } from '../execute-fetch';
+import { describeServeBuilder } from '../jasmine-helpers';
+import { BASE_OPTIONS, DEV_SERVER_BUILDER_INFO } from '../setup';
+
+describeServeBuilder(executeDevServer, DEV_SERVER_BUILDER_INFO, (harness, setupTarget) => {
+  describe('option: "hmr"', () => {
+    beforeEach(async () => {
+      setupTarget(harness, {});
+    });
+
+    it('shows message with opt out steps by default', async () => {
+      harness.useTarget('serve', {
+        ...BASE_OPTIONS,
+      });
+
+      const { result, logs } = await executeOnceAndFetch(harness, '/');
+
+      expect(result?.success).toBeTrue();
+      expect(logs).toContain(
+        jasmine.objectContaining<logging.LogEntry>({
+          message: jasmine.stringMatching('Component HMR has been enabled'),
+        }),
+      );
+      expect(logs).toContain(
+        jasmine.objectContaining<logging.LogEntry>({
+          message: jasmine.stringMatching('--no-hmr'),
+        }),
+      );
+    });
+
+    it('shows message with opt out steps when explicitly enabled', async () => {
+      harness.useTarget('serve', {
+        ...BASE_OPTIONS,
+        hmr: true,
+      });
+
+      const { result, logs } = await executeOnceAndFetch(harness, '/');
+
+      expect(result?.success).toBeTrue();
+      expect(logs).toContain(
+        jasmine.objectContaining<logging.LogEntry>({
+          message: jasmine.stringMatching('Component HMR has been enabled'),
+        }),
+      );
+      expect(logs).toContain(
+        jasmine.objectContaining<logging.LogEntry>({
+          message: jasmine.stringMatching('--no-hmr'),
+        }),
+      );
+    });
+
+    it('does not show enabled message with opt out steps when explicitly disabled', async () => {
+      harness.useTarget('serve', {
+        ...BASE_OPTIONS,
+        hmr: false,
+      });
+
+      const { result, logs } = await executeOnceAndFetch(harness, '/');
+
+      expect(result?.success).toBeTrue();
+      expect(logs).not.toContain(
+        jasmine.objectContaining<logging.LogEntry>({
+          message: jasmine.stringMatching('Component HMR has been enabled'),
+        }),
+      );
+      expect(logs).not.toContain(
+        jasmine.objectContaining<logging.LogEntry>({
+          message: jasmine.stringMatching('--no-hmr'),
+        }),
+      );
+    });
+  });
+});