Use mocha for sample tests (#119)

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

@@ -8,9 +8,7 @@
   "repository": "googleapis/nodejs-language",
   "private": true,
   "scripts": {
-    "ava": "ava -T 20s --verbose test/*.test.js ./system-test/*.test.js",
-    "cover": "nyc --reporter=lcov --cache ava -T 20s --verbose test/*.test.js ./system-test/*.test.js && nyc report",
-    "test": "npm run cover"
+    "test": "mocha"
   },
   "dependencies": {
     "@google-cloud/language": "^1.2.0",
@@ -19,7 +17,7 @@
   },
   "devDependencies": {
     "@google-cloud/nodejs-repo-tools": "^2.3.0",
-    "ava": "^0.25.0",
+    "mocha": "^5.2.0",
     "uuid": "^3.2.1"
   }
 }

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

@@ -0,0 +1,33 @@
+/**
+ * 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 path = require(`path`);
+const assert = require('assert');
+const tools = require(`@google-cloud/nodejs-repo-tools`);
+
+const cmd = `node quickstart.js`;
+const cwd = path.join(__dirname, `..`);
+
+beforeEach(async () => tools.stubConsole);
+afterEach(async () => tools.restoreConsole);
+
+it(`should analyze sentiment in text`, async () => {
+  const output = await tools.runAsync(cmd, cwd);
+  assert(RegExp('Text: Hello, world!').test(output));
+  assert(RegExp('Sentiment score: ').test(output));
+  assert(RegExp('Sentiment magnitude: ').test(output));
+});