add jest

babel.config.js

@@ -0,0 +1,12 @@
+module.exports = {
+  presets: [
+    [
+      '@babel/preset-env',
+      {
+        targets: {
+          node: 'current',
+        },
+      },
+    ],
+  ],
+};

package.json

@@ -5,5 +5,15 @@
     "minimist": "^1.2.5",
     "puppeteer": "^3.0.2",
     "ramda": "^0.27.0"
+  },
+  "devDependencies": {
+    "@babel/core": "^7.10.1",
+    "@babel/preset-env": "^7.10.1",
+    "babel-jest": "^26.0.1",
+    "jest": "^26.0.1"
+  },
+  "scripts": {
+    "test": "jest",
+    "watch": "jest --watch"
   }
 }