infrastructure(site) Add test task and use yarn to TravisCI (#2226)

* re-arrange ci scripts order

* add test task to pipeline

* npm -> yarn

* remove yarn installation

* fix: remaining linter issues

Author: byzyk

.travis.yml

@@ -5,10 +5,9 @@ branches:
 language: node_js
 node_js:
   - "8"
-script:
-  - bash ./src/scripts/deploy.sh
 sudo: required
 install:
-  - npm install --global yarn
   - yarn
   - sudo pip install proselint
+script:
+  - bash ./src/scripts/deploy.sh

src/content/concepts/mode.md

@@ -3,6 +3,7 @@ title: Mode
 sort: 4
 contributors:
   - EugeneHlushko
+  - byzyk
 ---
 
 Providing the `mode` configuration option tells webpack to use its built-in optimizations accordingly.
@@ -85,20 +86,20 @@ If you want to change the behavior according the **mode** variable inside the *w
 
 ```javascript
 var config = {
-  entry: "./app.js"
-  ..
-}
+  entry: './app.js'
+  //...
+};
 
 module.exports = (env, argv) => {
-  
-  if (argv.mode === "development") {
-    config.devtool = "source-map";
+
+  if (argv.mode === 'development') {
+    config.devtool = 'source-map';
   }
-  
-  if (argv.mode === "production") {
+
+  if (argv.mode === 'production') {
+    //...
   }
-  
-  return config;
-}
 
+  return config;
+};
 ```

src/scripts/deploy.sh

@@ -7,17 +7,20 @@ SOURCE_BRANCH="master"
 # Pull requests and commits to other branches shouldn't try to deploy, just build to verify
 if [ "$TRAVIS_PULL_REQUEST" != "false" -o "$TRAVIS_BRANCH" != "$SOURCE_BRANCH" ]; then
     echo "Skipping deploy; just doing a build and linting links/prose/js."
-    npm run build
-    npm test
+    yarn test
+    yarn build
     exit 0
 fi
 
 # Save some useful information
 REPO=`git config remote.origin.url`
 SSH_REPO=${REPO/https:\/\/github.com\//git@github.com:}
 
+# Run tests
+yarn test
+
 # Run our build
-npm run build
+yarn build
 
 # Set some git options
 git config --global user.name "Travis CI"
@@ -35,4 +38,4 @@ eval `ssh-agent -s`
 ssh-add src/scripts/deploy_key
 
 # Now that we're all set up, we can deploy
-npm run deploy
+yarn deploy