fix(AbstractHistory): Fix router.back in abstract mode

Fix abstract mode's router.back() when 2 consecutive same routes appear in the history stack array

fix #2607

src/history/abstract.js

@@ -37,6 +37,10 @@ export class AbstractHistory extends History {
     this.confirmTransition(route, () => {
       this.index = targetIndex
       this.updateRoute(route)
+    }, (err) => {
+      if (err === 'SAME_ROUTE') {
+        this.index = targetIndex
+      }
     })
   }
 

src/history/base.js

@@ -103,7 +103,7 @@ export class History {
       route.matched.length === current.matched.length
     ) {
       this.ensureURL()
-      return abort()
+      return abort('SAME_ROUTE')
     }
 
     const {

test/unit/specs/node.spec.js

@@ -35,4 +35,21 @@ describe('Usage in Node', () => {
     expect(router.getMatchedComponents('/')).toEqual([Foo])
     expect(router.getMatchedComponents('/bar/baz')).toEqual([Bar, Baz])
   })
+
+  it('should navigate through history with same consecutive routes in history stack', () => {
+    const router = new VueRouter({
+      routes: [
+        { path: '/', component: { name: 'foo' }},
+        { path: '/bar', component: { name: 'bar' }}
+      ]
+    })
+    router.push('/')
+    router.push('/bar')
+    router.push('/')
+    router.replace('/bar')
+    router.back()
+    expect(router.history.current.path).toBe('/bar')
+    router.back()
+    expect(router.history.current.path).toBe('/')
+  })
 })