Improve code quality and write tests

node_modules/codecov/lib/services/heroku.js

@@ -0,0 +1,17 @@
+// https://devcenter.heroku.com/articles/heroku-ci
+
+module.exports = {
+  detect: function() {
+    return !!process.env.HEROKU_TEST_RUN_ID
+  },
+
+  configuration: function() {
+    console.log('    heroku CI Detected')
+    return {
+      service: 'heroku',
+      build: process.env.HEROKU_TEST_RUN_ID,
+      commit: process.env.HEROKU_TEST_RUN_COMMIT_VERSION,
+      branch: process.env.HEROKU_TEST_RUN_BRANCH,
+    }
+  },
+}