Add CircleCI (#3)

.circleci/config.yml

@@ -0,0 +1,31 @@
+# JavaScript Node CircleCI 2.0 configuration file
+#
+# Check https://circleci.com/docs/2.0/language-javascript/ for more details
+#
+version: 2
+jobs:
+  build:
+    docker:
+      # specify the version you desire here
+      - image: circleci/node:10
+
+    steps:
+      - checkout
+
+      # Download and cache dependencies
+      - restore_cache:
+          keys:
+            - v1-dependencies-{{ checksum "yarn.lock" }}
+            # fallback to using the latest cache if no exact match is found
+            - v1-dependencies-
+
+      - run: yarn --frozen-lockfile
+
+      - save_cache:
+          key: v1-dependencies-{{ checksum "yarn.lock" }}
+          paths:
+            - ~/.cache/yarn
+
+      - run: yarn test
+
+      - run: yarn build