diff --git a/app/src/lib/switchToLanguage.test.ts b/app/src/lib/switchToLanguage.test.ts
new file mode 100644
index 0000000..32c9797
--- /dev/null
+++ b/app/src/lib/switchToLanguage.test.ts
@@ -0,0 +1,40 @@
+import { describe, it, expect, vi } from 'vitest';
+import { switchToLanguage } from './switchToLanguage';
+import { i18n } from '$lib/i18n';
+import { goto } from '$app/navigation';
+
+vi.mock('$lib/i18n', () => ({
+    i18n: {
+        route: vi.fn().mockImplementation((translatedPath: string) => ''),
+        resolveRoute: vi.fn().mockImplementation((path: string, lang?: string) => '')
+    }
+}));
+
+vi.mock('$app/state', () => ({
+    page: {
+        url: {
+            pathname: '/current-path'
+        }
+    }
+}));
+
+vi.mock('$app/navigation', () => ({
+    goto: vi.fn()
+}));
+
+describe('switchToLanguage', () => {
+    it('should switch to the new language', () => {
+        const newLanguage = 'en';
+        const canonicalPath = '/canonical-path';
+        const localisedPath = '/en/canonical-path';
+
+        i18n.route.mockReturnValue(canonicalPath);
+        i18n.resolveRoute.mockReturnValue(localisedPath);
+
+        switchToLanguage(newLanguage);
+
+        expect(i18n.route).toHaveBeenCalledWith('/current-path');
+        expect(i18n.resolveRoute).toHaveBeenCalledWith(canonicalPath, newLanguage);
+        expect(goto).toHaveBeenCalledWith(localisedPath);
+    });
+});
\ No newline at end of file
diff --git a/app/src/lib/switchToLanguage.ts b/app/src/lib/switchToLanguage.ts
new file mode 100644
index 0000000..13d5fc8
--- /dev/null
+++ b/app/src/lib/switchToLanguage.ts
@@ -0,0 +1,10 @@
+import type { AvailableLanguageTag } from '$lib/paraglide/runtime';
+import { i18n } from '$lib/i18n';
+import { page } from '$app/state';
+import { goto } from '$app/navigation';
+
+export function switchToLanguage(newLanguage: AvailableLanguageTag) {
+    const canonicalPath = i18n.route(page.url.pathname);
+    const localisedPath = i18n.resolveRoute(canonicalPath, newLanguage);
+    goto(localisedPath);
+}
\ No newline at end of file
diff --git a/app/src/routes/demo/+page.svelte b/app/src/routes/demo/+page.svelte
deleted file mode 100644
index a815390..0000000
--- a/app/src/routes/demo/+page.svelte
+++ /dev/null
@@ -1 +0,0 @@
-<a href="/demo/paraglide">paraglide</a>
diff --git a/app/src/routes/demo/paraglide/+page.svelte b/app/src/routes/demo/paraglide/+page.svelte
deleted file mode 100644
index c47b06f..0000000
--- a/app/src/routes/demo/paraglide/+page.svelte
+++ /dev/null
@@ -1,19 +0,0 @@
-<script lang="ts">
-	import type { AvailableLanguageTag } from '$lib/paraglide/runtime';
-	import { i18n } from '$lib/i18n';
-	import { page } from '$app/state';
-	import { goto } from '$app/navigation';
-	import * as m from '$lib/paraglide/messages.js';
-
-	function switchToLanguage(newLanguage: AvailableLanguageTag) {
-		const canonicalPath = i18n.route(page.url.pathname);
-		const localisedPath = i18n.resolveRoute(canonicalPath, newLanguage);
-		goto(localisedPath);
-	}
-</script>
-
-<h1>{m.hello_world({ name: 'SvelteKit User' })}</h1>
-<div>
-	<button onclick={() => switchToLanguage('en')}>en</button>
-	<button onclick={() => switchToLanguage('hu')}>hu</button>
-</div>