Add testing via jest.

Author: StevenXL

package.json

@@ -5,7 +5,9 @@
   "main": "dist/index.js",
   "scripts": {
     "build": "babel src -o dist/index.js",
-    "dev": "watch 'yarn run build' src"
+    "dev": "watch 'yarn run build' src",
+    "test": "jest",
+    "test:watch": "yarn run test -- --watch"
   },
   "babel": {
     "presets": [
@@ -20,6 +22,7 @@
     "@babel/cli": "^7.17.6",
     "@babel/core": "^7.17.9",
     "@babel/preset-env": "^7.16.11",
+    "jest": "^27.5.1",
     "watch": "^1.0.2"
   }
 }

src/index.test.js

@@ -0,0 +1,7 @@
+import { helloWord } from ".";
+
+describe("helloWord", () => {
+  test("is hello world", () => {
+    expect(helloWord()).toBe("Hello, World!");
+  });
+});