Setup with Yarn

* Updates makefile to use yarn install instead of npm install
* Use `yarn install --frozen-lockfile` on CI to ensure deps cannot be commited accidentally
* generate an initial lockfile

Author: f2prateek

.circleci/config.yml

@@ -7,10 +7,10 @@ jobs:
       - checkout
       - run: npm config set "//registry.npmjs.org/:_authToken" $NPM_AUTH
       - restore_cache:
-          key: dependency-cache-{{ checksum "package.json" }}
-      - run: make install
+          key: yarn-dependency-cache-{{ checksum "yarn.lock" }}
+      - run: yarn install --frozen-lockfile
       - save_cache:
-          key: dependency-cache-{{ checksum "package.json" }}
+          key: yarn-dependency-cache-{{ checksum "yarn.lock" }}
           paths:
             - node_modules
       - run: make test

Makefile

@@ -42,13 +42,9 @@ GREP ?= .
 # Tasks
 ##
 
-# Install node modules.
-node_modules: package.json $(wildcard node_modules/*/package.json)
-	@npm install
-	@touch $@
-
 # Install dependencies.
-install: node_modules
+install:
+	yarn
 
 # Remove temporary files and build artifacts.
 clean: