Automate testing Torbutton's 'New Identity' feature

Will-fix: #9286

features/step_definitions/common_steps.rb

@@ -369,7 +369,7 @@ Given /^the Tor Browser has started$/ do
   @screen.wait(tor_browser_picture, 60)
 end
 
-Given /^the Tor Browser has started and loaded the (startup page|Tails roadmap)$/ do |page|
+Given /^the Tor Browser (?:has started and )?load(?:ed|s)? the (startup page|Tails roadmap)$/ do |page|
   next if @skip_steps_while_restoring_background
   case page
   when "startup page"

features/torified_browsing.feature

@@ -79,6 +79,15 @@ Feature: Browsing the web using the Tor Browser
     And I open the address "https://check.torproject.org" in the Tor Browser
     Then I see "TorBrowserTorCheck.png" after at most 180 seconds
 
+  Scenario: The Tor Browser's "New identity" feature works as expected
+    When I start the Tor Browser
+    And the Tor Browser has started and loaded the startup page
+    And I open the address "https://check.torproject.org" in the Tor Browser
+    Then I see "TorBrowserTorCheck.png" after at most 180 seconds
+    When I request a new identity using Torbutton
+    And I acknowledge Torbutton's New Identity confirmation prompt
+    Then the Tor Browser loads the startup page
+
   Scenario: The Tor Browser should not have any plugins enabled
     When I start the Tor Browser
     And the Tor Browser has started and loaded the startup page