build: Use yarn over npm (#331)

.circleci/config.yml

@@ -12,13 +12,13 @@ jobs:
       - checkout
       - restore_cache: &restore_cache
           keys:
-            - v2-yarn-{{checksum ".circleci/config.yml"}}-{{ checksum "package-lock.json"}}
+            - v2-yarn-{{checksum ".circleci/config.yml"}}-{{ checksum "yarn.lock"}}
       - run:
           name: Install project dependencies
-          command: npm ci
+          command: yarn
       - run:
           name: Install CI only dependencies
-          command: npm install -D --no-package-lock nyc@11 @oclif/nyc-config@1 mocha-junit-reporter@1
+          command: yarn add -D --no-lockfile nyc@11 @oclif/nyc-config@1 mocha-junit-reporter@1
       - run:
           name: Version command
           command: ./bin/run --version
@@ -52,7 +52,7 @@ jobs:
     <<: *test
     steps:
       - checkout
-      - run: npm ci
+      - run: yarn
       - run: npx semantic-release
       - run: ./release-percy.sh
 workflows:

CONTRIBUTING.md

@@ -25,7 +25,7 @@ Here is a summary of the steps to follow:
 $ git checkout master
 $ git pull upstream master
 $ rm -rf node_modules
-$ npm install
+$ yarn install
 ```
 3. Create a new topic branch (off the main project development branch) to contain your feature, change, or fix:
 ```bash
@@ -119,26 +119,26 @@ $ npm install
 
 [@percy/agent](https://github.com/percy/percy-agent) use [tslint](https://github.com/palantir/tslint) for linting.
 
-Before pushing your code changes make sure there are no linting errors with `npm run lint`.
+Before pushing your code changes make sure there are no linting errors with `yarn lint`.
 
 ### Tests
 
 You can run the tests with:
 
 ```bash
-$ npm run test
+$ yarn test
 ```
 
 You can test Percy Agent Client with
 
 ```bash
-$ npm run test-client
+$ yarn test-client
 ```
 
 And the integration tests can be run with:
 
 ```bash
-$ PERCY_TOKEN=xxx npm run test-integration
+$ PERCY_TOKEN=xxx yarn test-integration
 ```
 
 You can find `PERCY_TOKEN` on your Percy project settings.