[CI] Unit test webdriver script exit code depends on test failure

Unit test webdriver script now parses the Mocha test results XML to see
if any tests failed and if so, exit with a nonzero exit code, so that
CircleCI will report a CI failure

script/unit_test_webdriver.js

@@ -21,6 +21,8 @@ if (!baseDir) {
   process.exit(1);
 }
 
+var success = true
+
 var browserDriver = wd.promiseChainRemote('ondemand.saucelabs.com', 80, username, accessKey);
 browserDriver.init({
   browserName: 'Chrome',
@@ -40,12 +42,21 @@ browserDriver.init({
   fs.writeFileSync(baseDir + '/test-results.xml', resultsXML);
   console.log('Wrote to ' + baseDir + '/test-results.xml');
 
-  // TODO: exit status based on whether tests passed
+  const [_, failures, errors] = lines[0].match(/ failures="(\d+)" errors="(\d+)"/)
+  console.log(failures + ' failures, ' + errors + ' errors');
+  success = (failures + errors === 0);
 })
 .fail(function(err) {
   console.log('ERROR:', JSON.stringify(err, null, 2));
+  success = false;
+})
+.then(function() {
+  return browserDriver.sauceJobStatus(success);
 })
-.quit();
+.quit()
+.then(function() {
+  process.exit(success ? 0 : 1);
+});
 
 function willLog() {
   var msg = [].join.call(arguments, ' ');