refactor login as to be impersonation with better login/logout

Modifies the existing "login as" feature to be called impersonation, as
well as keeping track of who is impersonating to revert back to that
user without having to log out.

app/assets/stylesheets/framework/header.scss

@@ -118,6 +118,10 @@ header {
       }
     }
   }
+
+  .impersonation i {
+    color: $red-normal;
+  }
 }
 
 @mixin collapsed-header {

app/controllers/admin/application_controller.rb

@@ -8,4 +8,10 @@ class Admin::ApplicationController < ApplicationController
   def authenticate_admin!
     return render_404 unless current_user.is_admin?
   end
+
+  def authorize_impersonator!
+    if session[:impersonator_id]
+      User.find_by!(username: session[:impersonator_id]).admin?
+    end
+  end
 end

app/controllers/admin/impersonation_controller.rb

+class Admin::ImpersonationController < Admin::ApplicationController
+  skip_before_action :authenticate_admin!, only: :destroy
+
+  before_action :user
+  before_action :authorize_impersonator!
+
+  def create
+    session[:impersonator_id] = current_user.username
+    session[:impersonator_return_to] = request.env['HTTP_REFERER']
+
+    warden.set_user(user, scope: 'user')
+
+    flash[:alert] = "You are impersonating #{user.username}."
+
+    redirect_to root_path
+  end
+
+  def destroy
+    redirect = session[:impersonator_return_to]
+
+    warden.set_user(user, scope: 'user')
+
+    session[:impersonator_return_to] = nil
+    session[:impersonator_id] = nil
+
+    redirect_to redirect || root_path
+  end
+
+  def user
+    @user ||= User.find_by!(username: params[:id] || session[:impersonator_id])
+  end
+end

app/controllers/admin/users_controller.rb

@@ -63,12 +63,6 @@ class Admin::UsersController < Admin::ApplicationController
     end
   end
 
-  def login_as
-    sign_in(user)
-    flash[:alert] = "Logged in as #{user.username}"
-    redirect_to root_path
-  end
-
   def disable_two_factor
     user.disable_two_factor!
     redirect_to admin_user_path(user),

app/views/admin/users/_head.html.haml

@@ -7,7 +7,7 @@
 
   .pull-right
     - unless @user == current_user
-      = link_to 'Log in as this user', login_as_admin_user_path(@user), method: :post, class: "btn btn-grouped btn-info"
+      = link_to 'Impersonate', impersonate_admin_user_path(@user), method: :post, class: "btn btn-grouped btn-info"
     = link_to edit_admin_user_path(@user), class: "btn btn-grouped" do
       %i.fa.fa-pencil-square-o
       Edit

app/views/layouts/header/_default.html.haml

@@ -13,6 +13,10 @@
           %li.visible-sm.visible-xs
             = link_to search_path, title: 'Search', data: {toggle: 'tooltip', placement: 'bottom'} do
               = icon('search')
+          - if session[:impersonator_id]
+            %li.impersonation
+              = link_to stop_impersonation_admin_users_path, method: :delete, title: 'Stop impersonation', data: { toggle: 'tooltip', placement: 'bottom' } do
+                = icon('user-secret fw')
           - if current_user.is_admin?
             %li
               = link_to admin_root_path, title: 'Admin area', data: {toggle: 'tooltip', placement: 'bottom'} do

config/routes.rb

@@ -212,6 +212,8 @@ Gitlab::Application.routes.draw do
       resources :keys, only: [:show, :destroy]
       resources :identities, only: [:index, :edit, :update, :destroy]
 
+      delete 'stop_impersonation' => 'impersonation#destroy', on: :collection
+
       member do
         get :projects
         get :keys
@@ -221,7 +223,7 @@ Gitlab::Application.routes.draw do
         put :unblock
         put :unlock
         put :confirm
-        post :login_as
+        post 'impersonate' => 'impersonation#create'
         patch :disable_two_factor
         delete 'remove/:email_id', action: 'remove_email', as: 'remove_email'
       end

spec/controllers/admin/users_controller_spec.rb

@@ -7,21 +7,6 @@ describe Admin::UsersController do
     sign_in(admin)
   end
 
-  describe 'POST login_as' do
-    let(:user) { create(:user) }
-
-    it 'logs admin as another user' do
-      expect(warden.authenticate(scope: :user)).not_to eq(user)
-      post :login_as, id: user.username
-      expect(warden.authenticate(scope: :user)).to eq(user)
-    end
-
-    it 'redirects user to homepage' do
-      post :login_as, id: user.username
-      expect(response).to redirect_to(root_path)
-    end
-  end
-
   describe 'DELETE #user with projects' do
     let(:user) { create(:user) }
     let(:project) { create(:project, namespace: user.namespace) }

spec/features/admin/admin_users_spec.rb

@@ -111,24 +111,50 @@ describe "Admin::Users", feature: true  do
       expect(page).to have_content(@user.name)
     end
 
-    describe 'Login as another user' do
-      it 'should show login button for other users and check that it works' do
-        another_user = create(:user)
+    describe 'Impersonation' do
+      let(:another_user) { create(:user) }
+      before { visit admin_user_path(another_user) }
 
-        visit admin_user_path(another_user)
+      context 'before impersonating' do
+        it 'shows impersonate button for other users' do
+          expect(page).to have_content('Impersonate')
+        end
+
+        it 'should not show impersonate button for admin itself' do
+          visit admin_user_path(@user)
 
-        click_link 'Log in as this user'
+          expect(page).not_to have_content('Impersonate')
+        end
+      end
 
-        expect(page).to have_content("Logged in as #{another_user.username}")
+      context 'when impersonating' do
+        before { click_link 'Impersonate' }
 
+        it 'logs in as the user when impersonate is clicked' do
           page.within '.sidebar-user .username' do
             expect(page).to have_content(another_user.username)
           end
         end
 
-      it 'should not show login button for admin itself' do
-        visit admin_user_path(@user)
-        expect(page).not_to have_content('Log in as this user')
+        it 'sees impersonation log out icon' do
+          icon = first('.fa.fa-user-secret')
+
+          expect(icon).to_not eql nil
+        end
+
+        it 'can log out of impersonated user back to original user' do
+          find(:css, 'li.impersonation a').click
+
+          page.within '.sidebar-user .username' do
+            expect(page).to have_content(@user.username)
+          end
+        end
+
+        it 'is redirected back to the impersonated users page in the admin after stopping' do
+          find(:css, 'li.impersonation a').click
+
+          expect(current_path).to eql "/admin/users/#{another_user.username}"
+        end
       end
     end