🐛 Fixed admin URL not updating when changing tag slug

closes https://github.com/TryGhost/Ghost/issues/9571
- uses `window.replaceState` to update the URL when a tag is saved with a new URL
    - ensures back button doesn't result in 404
    - use `windowProxy` util so that behaviour can be tested

ghost/admin/app/controllers/settings/tags/tag.js

@@ -1,4 +1,5 @@
 import Controller, {inject as controller} from '@ember/controller';
+import windowProxy from 'ghost-admin/utils/window-proxy';
 import {alias} from '@ember/object/computed';
 import {inject as service} from '@ember/service';
 
@@ -28,6 +29,7 @@ export default Controller.extend({
 
     _saveTagProperty(propKey, newValue) {
         let tag = this.get('tag');
+        let isNewTag = tag.get('isNew');
         let currentValue = tag.get(propKey);
 
         if (newValue) {
@@ -46,6 +48,17 @@ export default Controller.extend({
         tag.save().then((savedTag) => {
             // replace 'new' route with 'tag' route
             this.replaceRoute('settings.tags.tag', savedTag);
+
+            // update the URL if the slug changed
+            if (propKey === 'slug' && !isNewTag) {
+                let currentPath = window.location.hash;
+
+                let newPath = currentPath.split('/');
+                newPath[newPath.length - 1] = savedTag.get('slug');
+                newPath = newPath.join('/');
+
+                windowProxy.replaceState({path: newPath}, '', newPath);
+            }
         }).catch((error) => {
             if (error) {
                 this.get('notifications').showAPIError(error, {key: 'tag.save'});

ghost/admin/app/controllers/team/user.js

@@ -435,17 +435,14 @@ export default Controller.extend({
         }
 
         try {
-            let currentPath,
-                newPath;
-
             user = yield user.save({format: false});
 
             // If the user's slug has changed, change the URL and replace
             // the history so refresh and back button still work
             if (slugChanged) {
-                currentPath = window.location.hash;
+                let currentPath = window.location.hash;
 
-                newPath = currentPath.split('/');
+                let newPath = currentPath.split('/');
                 newPath[newPath.length - 1] = user.get('slug');
                 newPath = newPath.join('/');
 

ghost/admin/tests/acceptance/settings/tags-test.js

@@ -3,6 +3,7 @@ import $ from 'jquery';
 import destroyApp from '../../helpers/destroy-app';
 import startApp from '../../helpers/start-app';
 import wait from 'ember-test-helpers/wait';
+import windowProxy from 'ghost-admin/utils/window-proxy';
 import {Response} from 'ember-cli-mirage';
 import {afterEach, beforeEach, describe, it} from 'mocha';
 import {authenticateSession, invalidateSession} from 'ghost-admin/tests/helpers/ember-simple-auth';
@@ -77,13 +78,25 @@ describe('Acceptance: Settings - Tags', function () {
     });
 
     describe('when logged in', function () {
+        let newLocation, originalReplaceState;
+
         beforeEach(function () {
             let role = server.create('role', {name: 'Administrator'});
             server.create('user', {roles: [role]});
 
+            originalReplaceState = windowProxy.replaceState;
+            windowProxy.replaceState = function (params, title, url) {
+                newLocation = url;
+            };
+            newLocation = undefined;
+
             return authenticateSession(application);
         });
 
+        afterEach(function () {
+            windowProxy.replaceState = originalReplaceState;
+        });
+
         it('it renders, can be navigated, can edit, create & delete tags', async function () {
             let tag1 = server.create('tag');
             let tag2 = server.create('tag');
@@ -267,6 +280,25 @@ describe('Acceptance: Settings - Tags', function () {
                 .to.equal('internal');
         });
 
+        it('updates the URL when slug changes', async function () {
+            server.createList('tag', 2);
+
+            await visit('/settings/tags/tag-1');
+
+            // second wait is needed for the vertical-collection to settle
+            await wait();
+
+            expect(currentURL(), 'URL after direct load').to.equal('/settings/tags/tag-1');
+
+            // update the slug
+            await fillIn('.tag-settings-pane input[name="slug"]', 'test');
+            await triggerEvent('.tag-settings-pane input[name="slug"]', 'blur');
+
+            // tests don't have a location.hash so we can only check that the
+            // slug portion is updated correctly
+            expect(newLocation, 'URL after slug change').to.equal('test');
+        });
+
         it('redirects to 404 when tag does not exist', async function () {
             server.get('/tags/slug/unknown/', function () {
                 return new Response(404, {'Content-Type': 'application/json'}, {errors: [{message: 'Tag not found.', errorType: 'NotFoundError'}]});