do not require ruby-debug automatically. please require it if you have declared it as a dependency

actionpack/test/abstract_unit.rb

@@ -36,14 +36,6 @@ require 'active_record'
 require 'action_controller/caching'
 require 'action_controller/caching/sweeping'
 
-begin
-  require 'ruby-debug'
-  Debugger.settings[:autoeval] = true
-  Debugger.start
-rescue LoadError
-  # Debugging disabled. `gem install ruby-debug` to enable.
-end
-
 require 'pp' # require 'pp' early to prevent hidden_methods from not picking up the pretty-print methods until too late
 
 module Rails

activemodel/test/cases/helper.rb

@@ -12,9 +12,3 @@ ActiveSupport::Deprecation.debug = true
 
 require 'rubygems'
 require 'test/unit'
-
-begin
-  require 'ruby-debug'
-  Debugger.start
-rescue LoadError
-end

activerecord/test/cases/helper.rb

@@ -13,11 +13,6 @@ require 'active_record'
 require 'active_support/dependencies'
 require 'connection'
 
-begin
-  require 'ruby-debug'
-rescue LoadError
-end
-
 # Show backtraces for deprecated behavior for quicker cleanup.
 ActiveSupport::Deprecation.debug = true
 

railties/lib/rails/test_help.rb

@@ -39,14 +39,3 @@ class ActionDispatch::IntegrationTest
     @routes = Rails.application.routes
   end
 end
-
-begin
-  require_library_or_gem 'ruby-debug'
-  Debugger.start
-  if Debugger.respond_to?(:settings)
-    Debugger.settings[:autoeval] = true
-    Debugger.settings[:autolist] = 1
-  end
-rescue LoadError
-  # ruby-debug wasn't available so neither can the debugging be
-end