fixed some frontend tests

frontend/src/__tests__/App.spec.ts

@@ -1,11 +1,18 @@
 import { describe, it, expect } from 'vitest'
 import { mount } from '@vue/test-utils'
+import { createMemoryHistory, createRouter } from 'vue-router'
 import App from '../App.vue'
 
+const mockRouter = createRouter({
+  history: createMemoryHistory(),
+  routes: [{ path: '/', name: 'Home', component: { template: '<div />' } }],
+})
+
 describe('App', () => {
   it('mounts renders properly', () => {
     const wrapper = mount(App, {
       global: {
+        plugins: [mockRouter],
         stubs: {
           'router-view': {
             template: '<div>You did it!</div>',