add jest

Author: Ambrozy

README.md

@@ -3,3 +3,9 @@
 A guessing game built with React and bundled using Vite.
 
 Try it now: https://ambrozy.github.io/iguessgame/
+
+## Running tests
+
+```bash
+npm test
+```

babel.config.cjs

@@ -0,0 +1,5 @@
+module.exports = {
+  presets: [
+    ['@babel/preset-env', { targets: { node: 'current' } }]
+  ],
+};

jest.config.js

@@ -0,0 +1,3 @@
+export default {
+  testEnvironment: 'node'
+};