Make live_debug and CHROME_HEADLESS cooperate

When using CHROME_HEADLESS=0 you can already have a logged-in session on
the page, so no need to open the user's browser as well

doc/development/testing_guide/best_practices.md

@@ -133,6 +133,8 @@ CHROME_HEADLESS=0 bundle exec rspec some_spec.rb
 ```
 The test will go by quickly, but this will give you an idea of what's happening.
+Using `live_debug` with `CHROME_HEADLESS=0` pauses the open browser, and does not
+open the page again. This can be used to debug and inspect elements.
 You can also add `byebug` or `binding.pry` to pause execution and [step through](../pry_debugging.md#stepping)
 the test.

spec/support/helpers/live_debugger.rb

@@ -6,11 +6,17 @@ module LiveDebugger
   def live_debug
     puts
     puts "Current example is paused for live debugging."
-    puts "Opening #{current_url} in your default browser..."
+
+    if ENV['CHROME_HEADLESS'] =~ /^(false|no|0)$/i
+      puts "Switch to the Chrome window that was automatically opened to run the test in order to view current page"
+    else
+      puts "Opening #{current_url} in your default browser..."
+    end
+
     puts "The current user credentials are: #{@current_user.username} / #{@current_user.password}" if @current_user
     puts "Press any key to resume the execution of the example!!"
-    `open #{current_url}`
+    `open #{current_url}` if ENV['CHROME_HEADLESS'] !~ /^(false|no|0)$/i
     loop until $stdin.getch