result

213-138-232-39:mri_instrumentation lourens$ rake
(in /Users/lourens/projects/mri_instrumentation)
/opt/local/bin/ruby -I"/Users/lourens/projects/mri_instrumentation/lib" -I"/Users/lourens/projects/mri_instrumentation/lib" "/Users/lourens/.gem/ruby/1.8/gems/rake-0.8.4/lib/rake/rake_test_loader.rb" "test/instrumentation/argument_test.rb" "test/instrumentation/definition_test.rb" "test/instrumentation/probe_collection_test.rb" "test/instrumentation/probe_test.rb" "test/instrumentation/runner_test.rb" "test/instrumentation/strategy/base_test.rb" "test/instrumentation/strategy/builder_test.rb" "test/instrumentation/strategy/calltime_test.rb" "test/instrumentation_test.rb" 
/Users/lourens/.gem/ruby/1.8/gems/rake-0.8.4/lib/rake.rb:990: warning: Insecure world writable dir /Users/lourens in PATH, mode 040753
Loaded suite /Users/lourens/.gem/ruby/1.8/gems/rake-0.8.4/lib/rake/rake_test_loader
Started
......................................Tracing... Hit Ctrl-C to end.

Count,
   Probe         COUNT
   rb_newobj      5637

Exclusive function elapsed times (us),
   Probe         TOTAL
   rb_newobj     21217

Inclusive function elapsed times (us),
   Probe         TOTAL
   rb_newobj     21217

.....
Finished in 0.584442 seconds.

runner_from_test.rb

  test "should be able to run it's strategy" do
    @runner.probes :rb_newobj
    @runner.command "ruby #{Mri::Instrumentation::Test::TARGET}"
    @runner.strategy :calltime  
    @runner.run!
  end 

target.rb

class Target
  
  def initialize( runs )
    @runs = runs
  end
  
  def run!
    @runs.times do
      Time.now
    end  
  end
  
end

Target.new(1000).run!