refactor: use execSync for tests (#237)

packages/google-cloud-translate/samples/.eslintrc.yml

@@ -1,3 +1,4 @@
 ---
 rules:
   no-console: off
+  node/no-missing-require: off

packages/google-cloud-translate/samples/package.json

@@ -8,7 +8,7 @@
     "node": ">=8"
   },
   "scripts": {
-    "test": "mocha system-test --recursive --timeout 90000"
+    "test": "mocha --recursive --timeout 90000"
   },
   "dependencies": {
     "@google-cloud/translate": "^3.0.0",
@@ -17,7 +17,6 @@
   },
   "devDependencies": {
     "chai": "^4.2.0",
-    "execa": "^1.0.0",
     "@google-cloud/storage": "^2.4.3",
     "mocha": "^6.0.0",
     "uuid": "^3.3.2"

packages/google-cloud-translate/samples/test/quickstart.test.js

@@ -0,0 +1,32 @@
+/**
+ * Copyright 2017, Google, Inc.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+'use strict';
+
+const {assert} = require('chai');
+const cp = require('child_process');
+const path = require('path');
+
+const execSync = cmd => cp.execSync(cmd, {encoding: 'utf-8'});
+
+const cwd = path.join(__dirname, '..');
+const projectId = process.env.GCLOUD_PROJECT;
+
+describe('quickstart sample tests', () => {
+  it('should translate a string', async () => {
+    const stdout = execSync(`node quickstart ${projectId}`, {cwd});
+    assert.match(stdout, new RegExp('Translation: Привет, мир!'));
+  });
+});