Add support for optimized requires.

lib/rspec/support.rb

@@ -1,7 +1,33 @@
-require "rspec/support/version"
-
 module RSpec
   module Support
+    # @api private
+    #
+    # Defines a helper method that is optimized to require files from the
+    # named lib. The passed block MUST be `{ |f| require_relative f }`
+    # because for `require_relative` to work properly from within the named
+    # lib the line of code must be IN that lib.
+    #
+    # `require_relative` is preferred when available because it is always O(1),
+    # regardless of the number of dirs in $LOAD_PATH. `require`, on the other
+    # hand, does a linear O(N) search over the dirs in the $LOAD_PATH until
+    # it can resolve the file relative to one of the dirs.
+    def self.define_optimized_require_for_rspec(lib, &require_relative)
+      name = "require_rspec_#{lib}"
+
+      if Kernel.respond_to?(:require_relative)
+        (class << self; self; end).__send__(:define_method, name) do |f|
+          require_relative.call("#{lib}/#{f}")
+        end
+      else
+        (class << self; self; end).__send__(:define_method, name) do |f|
+          require "rspec/#{lib}/#{f}"
+        end
+      end
+    end
+
+    define_optimized_require_for_rspec(:support) { |f| require_relative(f) }
+    require_rspec_support "version"
+
     # @api private
     KERNEL_METHOD_METHOD = ::Kernel.instance_method(:method)
 

lib/rspec/support/spec.rb

@@ -1,6 +1,7 @@
-require 'rspec/support/spec/deprecation_helpers'
-require 'rspec/support/spec/with_isolated_stderr'
-require 'rspec/support/spec/stderr_splitter'
+require 'rspec/support'
+RSpec::Support.require_rspec_support "spec/deprecation_helpers"
+RSpec::Support.require_rspec_support "spec/with_isolated_stderr"
+RSpec::Support.require_rspec_support "spec/stderr_splitter"
 
 warning_preventer = $stderr = RSpec::Support::StdErrSplitter.new($stderr)
 

spec/rspec/support/spec/stderr_splitter_spec.rb

@@ -19,9 +19,7 @@
   end
 
   it 'conforms to the stderr interface' do
-    stderr.methods.each do |method_name|
-      expect(splitter).to respond_to method_name
-    end
+    expect(splitter).to respond_to(*stderr.methods)
   end
 
   it 'behaves like stderr' do