fix(vue): go back to correct view with memory history

packages/vue-router/src/router.ts

@@ -120,7 +120,12 @@ export const createIonRouter = (opts: IonicVueRouterOptions, router: Router) =>
              * will go back in a linear fashion.
              */
             prevInfo.pathname === routeInfo.pushedByRoute &&
-            routeInfo.tab === '' && prevInfo.tab === ''
+
+            /**
+             * Tab info can be undefined or '' (empty string)
+             * both are false-y values, so we can just use !.
+             */
+            !routeInfo.tab && !prevInfo.tab
           )
         ) {
           router.back();

packages/vue/test-app/tests/unit/memory.spec.ts

@@ -0,0 +1,76 @@
+import { mount } from '@vue/test-utils';
+import { createRouter, createMemoryHistory } from '@ionic/vue-router';
+import {
+  IonContent,
+  IonHeader,
+  IonToolbar,
+  IonBackButton,
+  IonicVue,
+  IonApp,
+  IonRouterOutlet,
+  IonPage,
+} from '@ionic/vue';
+import { waitForRouter } from './utils';
+
+const App = {
+  components: { IonApp, IonRouterOutlet },
+  template: '<ion-app><ion-router-outlet /></ion-app>',
+}
+
+describe('createMemoryHistory', () => {
+  beforeAll(() => {
+    (HTMLElement.prototype as HTMLIonRouterOutletElement).commit = jest.fn();
+  });
+  it('should not error when going back with memory router', async () => {
+    const PageTemplate = {
+      template: `
+        <ion-page>
+          <ion-header>
+            <ion-toolbar>
+              <ion-back-button></ion-back-button>
+            </ion-toolbar>
+          </ion-header>
+          <ion-content></ion-content>
+        </ion-page>
+      `,
+      components: { IonPage, IonContent, IonHeader, IonToolbar, IonBackButton }
+    }
+
+    const router = createRouter({
+      history: createMemoryHistory(process.env.BASE_URL),
+      routes: [
+        { path: '/', component: PageTemplate },
+        { path: '/page2', component: PageTemplate },
+        { path: '/page3', component: PageTemplate }
+      ]
+    });
+    const push = jest.spyOn(router, 'back')
+
+    router.push('/');
+    await router.isReady();
+    const wrapper = mount(App, {
+      global: {
+        plugins: [router, IonicVue]
+      }
+    });
+
+    router.push('/page2');
+    await waitForRouter();
+
+    router.push('/page3');
+    await waitForRouter();
+
+
+    const backButtons = wrapper.findAllComponents(IonBackButton);
+    const pageTwoButton = backButtons[1];
+    const pageThreeButton = backButtons[2];
+
+    await pageThreeButton.trigger('click');
+    await waitForRouter();
+
+    await pageTwoButton.trigger('click');
+    await waitForRouter();
+
+    expect(push).toHaveBeenCalledTimes(2);
+  });
+})