test: add e2e test for dry run

Author: hansl

tests/e2e/tests/generate/service/service-dry-run.ts

@@ -0,0 +1,9 @@
+import {join} from 'path';
+import {ng} from '../../../utils/process';
+import {expectGitToBeClean} from '../../../utils/git';
+
+
+export default function() {
+  return ng('generate', 'service', 'test-service', '--module', 'app.module.ts', '--dry-run')
+    .then(() => expectGitToBeClean());
+}