Switch from Mocha to Ava for faster tests (#289)

* Switch from Mocha to Ava

* Concurrency: 5

Author: jmdobry

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

@@ -5,8 +5,7 @@
   "license": "Apache Version 2.0",
   "author": "Google Inc.",
   "scripts": {
-    "test": "cd ..; npm run t -- vision/test/*.test.js",
-    "system-test": "cd ..; npm run st -- vision/system-test/*.test.js"
+    "test": "cd ..; npm run st -- vision/system-test/*.test.js"
   },
   "dependencies": {
     "@google-cloud/vision": "0.7.0",

packages/google-cloud-vision/samples/quickstart.js

@@ -31,13 +31,11 @@ const visionClient = Vision({
 const fileName = './resources/wakeupcat.jpg';
 
 // Performs label detection on the image file
-visionClient.detectLabels(fileName, (err, labels) => {
-  if (err) {
-    console.error(err);
-    return;
-  }
+visionClient.detectLabels(fileName)
+  .then((results) => {
+    const labels = results[0];
 
-  console.log('Labels:');
-  labels.forEach((label) => console.log(label));
-});
+    console.log('Labels:');
+    labels.forEach((label) => console.log(label));
+  });
 // [END vision_quickstart]