feat: use yarn

.travis.yml

@@ -19,16 +19,16 @@ jobs:
       stage: test
       node_js: 'lts/carbon'
       script:
-        - npm run lint
-        - npm run test-ci
-        - npm install coveralls
+        - yarn lint
+        - yarn test-ci
+        - yarn add --no-lockfile coveralls rimraf
         # Report coverage to coveralls.io
         - cat ./__coverage__/lcov.info | ./node_modules/coveralls/bin/coveralls.js
-        - rm -fr ./__coverage__
+        - rimraf ./__coverage__
 
     -
       stage: deploy
       if: branch = master
       # Semantic release will fail if it's not using node 8.
       node_js: 'lts/carbon'
-      script: npm run semantic-release
+      script: yarn semantic-release

package.json

@@ -18,10 +18,10 @@
     "test": "NODE_ENV=test jest --coverage",
     "test-ci": "NODE_ENV=test jest --coverage --ci --runInBand",
     "commitmsg": "commitlint -e $GIT_PARAMS",
-    "precommit": "lint-staged && npm run flow",
+    "precommit": "lint-staged && yarn flow",
     "emdaer": "emdaer --yes && git add *.md",
-    "prepush": "npm run lint && npm run flow && npm test",
-    "prepublish": "npm run build",
+    "prepush": "yarn lint && yarn flow && yarn test",
+    "prepublish": "yarn build",
     "flow": "flow status",
     "build": "./node_modules/.bin/babel src -d lib --copy-files --delete-dir-on-start",
     "prettier": "prettier --write './**/*.js' && eslint './**/*.js' --fix",