Jest package and sample test

.eslintrc.js

@@ -2,16 +2,17 @@ module.exports = {
   env: {
     browser: true,
     es6: true,
-    node: true
+    node: true,
+    jest: true,
   },
   extends: "eslint:recommended",
   globals: {
     Atomics: "readonly",
-    SharedArrayBuffer: "readonly"
+    SharedArrayBuffer: "readonly",
   },
   parserOptions: {
     ecmaVersion: 2018,
-    sourceType: "module"
+    sourceType: "module",
   },
-  rules: {}
-};
+  rules: {},
+}

__tests__/example.test.js

+const sum = (a, b) => a + b
+
+describe("number adding", () => {
+  describe("number summation", () => {
+    it("adds 1 + 2 to equal 3", () => {
+      expect(sum(1, 2)).toBe(3)
+    })
+  })
+})

package.json

@@ -5,7 +5,8 @@
   "main": "index.js",
   "scripts": {
     "build": "webpack src/app.js -o public/js/app.js",
-    "start": "http-server -c-1 -p 12345 public"
+    "start": "http-server -c-1 -p 12345 public",
+    "test": "jest"
   },
   "dependencies": {
     "http-server": "^0.11.1",
@@ -17,6 +18,7 @@
     "yjs": "^12.3.3"
   },
   "devDependencies": {
+    "jest": "^24.9.0",
     "webpack": "^4.41.0",
     "webpack-cli": "^3.3.9"
   }