Fixes #3315 - nested "view from user perspective" yield to only being able to return to last viewed session

app/controllers/sessions_controller.rb

@@ -129,8 +129,8 @@ class SessionsController < ApplicationController
       return false
     end
 
-    # remember old user
-    session[:switched_from_user_id] = current_user.id
+    # remember original user
+    session[:switched_from_user_id] ||= current_user.id
 
     # log new session
     user.activity_stream_log('switch to', current_user.id, true)

spec/system/manage/users_spec.rb

@@ -0,0 +1,51 @@
+require 'rails_helper'
+
+RSpec.describe 'Manage > Users', type: :system do
+  describe 'switching to an alternative user', authenticated_as: -> { original_user } do
+    let(:original_user) { create(:admin) }
+    let(:alternative_one_user) { create(:admin) }
+    let(:alternative_two_user) { create(:admin) }
+
+    before do
+      alternative_one_user
+      alternative_two_user
+    end
+
+    it 'starts as original user' do
+      expect(current_user).to eq original_user
+    end
+
+    it 'switches to alternative user' do
+      switch_to(alternative_one_user)
+      expect(current_user).to eq alternative_one_user
+    end
+
+    it 'switches to another alternative user' do
+      switch_to(alternative_one_user)
+      switch_to(alternative_two_user)
+
+      expect(current_user).to eq alternative_two_user
+    end
+
+    it 'switches back to original user' do
+      switch_to(alternative_one_user)
+      switch_to(alternative_two_user)
+
+      click '.switchBackToUser-close'
+
+      expect(current_user).to eq original_user
+    end
+
+    def switch_to(user)
+      visit 'manage/users'
+
+      within(:active_content) do
+        row = find("tr[data-id=\"#{user.id}\"]")
+        row.find('.js-action').click
+        row.find('.js-switchTo').click
+      end
+
+      await_empty_ajax_queue
+    end
+  end
+end