Add tests

vite.config.ts

@@ -2,5 +2,10 @@ import { sveltekit } from '@sveltejs/kit/vite';
 import { defineConfig } from 'vite';
 
 export default defineConfig({
-	plugins: [sveltekit()]
+	plugins: [sveltekit()],
+	test: {
+		globals: true,
+		environment: 'node',
+		include: ['src/**/*.{test,spec}.{js,ts}']
+	}
 });