test(@angular/cli): add E2E test for file replacement watching

Author: clydin

tests/legacy-cli/e2e/tests/build/rebuild-replacements.ts

@@ -0,0 +1,31 @@
+import { getGlobalVariable } from '../../utils/env';
+import { appendToFile } from '../../utils/fs';
+import {
+  execAndWaitForOutputToMatch,
+  killAllProcesses,
+  waitForAnyProcessOutputToMatch,
+} from '../../utils/process';
+
+const webpackGoodRegEx = /: Compiled successfully./;
+
+export default async function() {
+  if (process.platform.startsWith('win')) {
+    return;
+  }
+
+  let error;
+  try {
+    await execAndWaitForOutputToMatch('ng', ['serve', '--prod'], webpackGoodRegEx);
+
+      // Should trigger a rebuild.
+    await appendToFile('src/environments/environment.prod.ts', `console.log('PROD');`);
+    await waitForAnyProcessOutputToMatch(webpackGoodRegEx, 30000);
+  } catch (e) {
+    error = e;
+  }
+
+  killAllProcesses();
+  if (error) {
+    throw error;
+  }
+}