refactor: modernize the sample tests (#164)

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

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

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

@@ -1,22 +1,25 @@
 {
   "name": "nodejs-docs-samples-text-to-speech",
-  "version": "0.0.1",
   "private": true,
   "license": "Apache-2.0",
   "author": "Google Inc.",
   "repository": "googleapis/nodejs-text-to-speech",
+  "files": [
+    "*.js"
+  ],
   "engines": {
     "node": ">=8"
   },
   "scripts": {
-    "test": "mocha system-test/*.test.js --timeout=600000"
+    "test": "mocha --timeout=60000"
   },
   "dependencies": {
     "@google-cloud/text-to-speech": "^0.4.0",
     "yargs": "^12.0.0"
   },
   "devDependencies": {
-    "@google-cloud/nodejs-repo-tools": "^3.0.0",
+    "chai": "^4.2.0",
+    "execa": "^1.0.0",
     "mocha": "^5.2.0"
   },
   "optionalDependencies": {

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

@@ -0,0 +1,39 @@
+/**
+ * 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 fs = require('fs');
+const {assert} = require('chai');
+const execa = require('execa');
+
+const outputFile = 'output.mp3';
+
+describe('quickstart', () => {
+  after(() => {
+    try {
+      fs.unlinkSync(outputFile);
+    } catch (err) {
+      // Ignore error
+    }
+  });
+
+  it('should synthesize speech to local mp3 file', async () => {
+    assert.strictEqual(fs.existsSync(outputFile), false);
+    const {stdout} = await execa.shell('node quickstart');
+    assert.match(stdout, /Audio content written to file: output.mp3/);
+    assert.ok(fs.existsSync(outputFile));
+  });
+});