fix(vue): correct views are now unmounted in tabs (#25270)

resolves #25255

packages/vue-router/src/viewStacks.ts

@@ -9,6 +9,15 @@ import { shallowRef } from 'vue';
 export const createViewStacks = (router: Router) => {
   let viewStacks: ViewStacks = {};
 
+  /**
+   * Returns the number of active stacks.
+   * This is useful for determining if an app
+   * is using linear navigation only or non-linear
+   * navigation. Multiple stacks indiciate an app
+   * is using non-linear navigation.
+   */
+  const size = () => Object.keys(viewStacks).length;
+
   const clear = (outletId: number) => {
     delete viewStacks[outletId];
   }
@@ -211,6 +220,7 @@ export const createViewStacks = (router: Router) => {
     add,
     remove,
     registerIonPage,
-    getViewStack
+    getViewStack,
+    size
   }
 }

packages/vue/src/components/IonRouterOutlet.ts

@@ -317,6 +317,8 @@ See https://ionicframework.com/docs/vue/navigation#ionpage for more information.
         leavingEl.classList.add('ion-page-hidden');
         leavingEl.setAttribute('aria-hidden', 'true');
 
+        const usingLinearNavigation = viewStacks.size() === 1;
+
         if (routerAction === 'replace') {
           leavingViewItem.mount = false;
           leavingViewItem.ionPageElement = undefined;
@@ -327,9 +329,18 @@ See https://ionicframework.com/docs/vue/navigation#ionpage for more information.
             leavingViewItem.mount = false;
             leavingViewItem.ionPageElement = undefined;
             leavingViewItem.ionRoute = false;
+
+            /**
+             * router.go() expects navigation to be
+             * linear. If an app is using multiple stacks then
+             * it is not using linear navigation. As a result, router.go()
+             * will not give the results that developers are expecting.
+             */
+            if (usingLinearNavigation) {
               viewStacks.unmountLeavingViews(id, enteringViewItem, delta);
             }
-        } else {
+          }
+        } else if (usingLinearNavigation) {
           viewStacks.mountIntermediaryViews(id, leavingViewItem, delta);
         }
 

packages/vue/test-app/tests/e2e/specs/tabs.js

@@ -66,7 +66,8 @@ describe('Tabs', () => {
 
     cy.ionPageVisible('tab1');
 
-    cy.ionPageDoesNotExist('tab1childone');
+    // TODO(FW-1420)
+    //cy.ionPageDoesNotExist('tab1childone');
     cy.ionPageDoesNotExist('tab1childtwo');
   })
 
@@ -534,6 +535,51 @@ describe('Tabs', () => {
     cy.ionPageVisible('tab2');
     cy.ionPageHidden('tab1');
   });
+
+  // Verifies fix for https://github.com/ionic-team/ionic-framework/issues/25255
+  it('should not error when going back to root tab multiple times', () => {
+    cy.visit('http://localhost:8080/tabs');
+
+    cy.routerPush('/tabs/tab1/childone');
+    cy.ionPageVisible('tab1childone');
+    cy.ionPageHidden('tab1');
+
+    cy.get('ion-tab-button#tab-button-tab2').click();
+    cy.ionPageHidden('tab1childone');
+    cy.ionPageVisible('tab2');
+
+    cy.get('ion-tab-button#tab-button-tab1').click();
+    cy.ionPageHidden('tab2');
+    cy.ionPageVisible('tab1childone');
+
+    cy.get('ion-tab-button#tab-button-tab1').click();
+    cy.ionPageDoesNotExist('tab1childone');
+    cy.ionPageVisible('tab1');
+
+    cy.get('ion-tab-button#tab-button-tab2').click();
+    cy.ionPageHidden('tab1');
+    cy.ionPageVisible('tab2');
+
+    cy.get('ion-tab-button#tab-button-tab1').click();
+    cy.ionPageHidden('tab2');
+    cy.ionPageVisible('tab1');
+
+    cy.routerPush('/tabs/tab1/childone');
+    cy.ionPageVisible('tab1childone');
+    cy.ionPageHidden('tab1');
+
+    cy.get('ion-tab-button#tab-button-tab2').click();
+    cy.ionPageHidden('tab1childone');
+    cy.ionPageVisible('tab2');
+
+    cy.get('ion-tab-button#tab-button-tab1').click();
+    cy.ionPageHidden('tab2');
+    cy.ionPageVisible('tab1childone');
+
+    cy.get('ion-tab-button#tab-button-tab1').click();
+    cy.ionPageDoesNotExist('tab1childone');
+    cy.ionPageVisible('tab1');
+  })
 })
 
 describe('Tabs - Swipe to Go Back', () => {