Add tests

Author: andrewda

.travis.yml

@@ -3,9 +3,9 @@ cache:
   yarn: true
   directories:
     - node_modules
-node_js:
-  - '7'
+node_js: '7'
 before_script:
-  - 'yarn'
+  - yarn
 script:
   - yarn run eslint
+  - yarn test