feat(@angular/cli): add flag to specify environment for ng test command

docs/documentation/test.md

@@ -66,6 +66,16 @@ You can run tests with coverage via `--code-coverage`. The coverage report will
   </p>
 </details>
 
+<details>
+  <summary>environment</summary>
+  <p>
+    <code>--environment</code> (aliases: <code>-e</code>)
+  </p>
+  <p>
+    Defines the build environment.
+  </p>
+</details>
+
 <details>
   <summary>log-level</summary>
   <p>

packages/@angular/cli/commands/test.ts

@@ -19,6 +19,7 @@ export interface TestOptions {
   progress?: boolean;
   config: string;
   poll?: number;
+  environment?: string;
   app?: string;
 }
 
@@ -100,6 +101,12 @@ const TestCommand = Command.extend({
       default: pollDefault,
       description: 'Enable and define the file watching poll time period (milliseconds).'
     },
+    {
+      name: 'environment',
+      type: String,
+      aliases: ['e'] ,
+      description: 'Defines the build environment.'
+    },
     {
       name: 'app',
       type: String,

packages/@angular/cli/tasks/test.ts

@@ -34,6 +34,7 @@ export default Task.extend({
         sourcemaps: options.sourcemaps,
         progress: options.progress,
         poll: options.poll,
+        environment: options.environment,
         app: options.app
       };
 

tests/e2e/tests/test/test-environment.ts

@@ -0,0 +1,28 @@
+import { ng } from '../../utils/process';
+import { writeFile } from '../../utils/fs';
+
+export default function () {
+  // Tests run in 'dev' environment by default.
+  return writeFile('src/app/environment.spec.ts', `
+      import { environment } from '../environments/environment';
+
+      describe('Test environment', () => {
+        it('should have production disabled', () => {
+          expect(environment.production).toBe(false);
+        });
+      });
+    `)
+    .then(() => ng('test', '--single-run'))
+
+    // Tests can run in different environment.
+    .then(() => writeFile('src/app/environment.spec.ts', `
+      import { environment } from '../environments/environment';
+
+      describe('Test environment', () => {
+        it('should have production enabled', () => {
+          expect(environment.production).toBe(true);
+        });
+      });
+    `))
+    .then(() => ng('test', '-e', 'prod', '--single-run'));
+}