migrate test framework

.travis.yml

@@ -5,7 +5,6 @@ cache:
     - $HOME/.yarn-cache
     - node_modules
 node_js:
-  - "6"
   - "8"
   - "10"
 before_install:
@@ -14,9 +13,5 @@ install:
   - yarn
 notifications:
     email: false
-before_script:
-  - yarn add codecov --dev
-after_script:
-  - codecov
 git:
   depth: 5