The default behaviour for non-rcov rake runs is 'in-process'

Previously, we shelled out via system calls to ruby, now we just
require the runner, disable the at exit hook, and the suite progresses
as normal.

lib/rspec/core/rake_task.rb

@@ -62,21 +62,30 @@ def define # :nodoc:
             if files_to_run.empty?
               puts "No examples matching #{pattern} could be found"
             else
-              cmd_parts = [
-                runner, 
-                runner_options,
-                '-Ilib',
-                '-Ispec'
-              ]
+              cmd_parts = [ '-Ilib', '-Ispec' ]
               cmd_parts << "-w" if warning
-              cmd_parts += files_to_run.map { |fn| %["#{fn}"] }
-              cmd = cmd_parts.join(" ")
-              puts cmd if verbose
 
-              unless system(cmd)
-                STDERR.puts failure_message if failure_message
-                raise("Command #{cmd} failed") if fail_on_error
+              if rcov
+                command_to_run = rcov_command(cmd_parts)
+                command_to_run.inspect if verbose
+
+                unless system(command_to_run)
+                  STDERR.puts failure_message if failure_message
+                  raise("#{command_to_run} failed") if fail_on_error
+                end
+              else
+                cmd_parts.concat(files_to_run)
+                puts cmd.inspect if verbose
+
+                require 'rspec/core'
+                RSpec::Core::Runner.disable_at_exit_hook!
+
+                unless RSpec::Core::Runner.run(cmd_parts, $stderr, $stdout)
+                  STDERR.puts failure_message if failure_message
+                  raise("RSpec::Core::Runner.run with args #{cmd_parts.inspect} failed") if fail_on_error
+                end
               end
+
             end
           end
         end
@@ -89,6 +98,14 @@ def files_to_run # :nodoc:
       end
 
       private
+
+      def rcov_command(cmd_parts)
+        cmd_parts.unshift runner_options
+        cmd_parts.unshift runner
+        cmd_parts += files_to_run.map { |fn| %["#{fn}"] }
+        cmd_parts.join(" ")
+      end
+
       def runner
         rcov ? rcov_path : RUBY
       end

lib/rspec/core/runner.rb

@@ -4,12 +4,20 @@ module RSpec
   module Core
     class Runner
 
+      def self.at_exit_hook_disabled?
+        @no_at_exit_hook ||= false
+      end
+
+      def self.disable_at_exit_hook!
+        @no_at_exit_hook = true
+      end
+
       def self.installed_at_exit?
         @installed_at_exit ||= false
       end
 
       def self.autorun
-        return if installed_at_exit? || running_in_drb?
+        return if at_exit_hook_disabled? || installed_at_exit? || running_in_drb?
         @installed_at_exit = true
         at_exit { run(ARGV, $stderr, $stdout) ? exit(0) : exit(1) }
       end

spec/rspec/core/runner_spec.rb

@@ -6,13 +6,15 @@ module RSpec::Core
       it 'sets an at_exit hook if none is already set' do
         RSpec::Core::Runner.stub(:installed_at_exit?).and_return(false)
         RSpec::Core::Runner.stub(:running_in_drb?).and_return(false)
+        RSpec::Core::Runner.stub(:at_exit_hook_disabled?).and_return(false)
         RSpec::Core::Runner.should_receive(:at_exit)
         RSpec::Core::Runner.autorun
       end
 
       it 'does not set the at_exit hook if it is already set' do
         RSpec::Core::Runner.stub(:installed_at_exit?).and_return(true)
         RSpec::Core::Runner.stub(:running_in_drb?).and_return(false)
+        RSpec::Core::Runner.stub(:at_exit_hook_disabled?).and_return(false)
         RSpec::Core::Runner.should_receive(:at_exit).never
         RSpec::Core::Runner.autorun
       end