Mocha VS MiniTest::Mock and SimpleDelegate VS SimpleMock

benchmark.rb

require 'benchmark'
require 'delegate'
require 'mocha'
require 'simple_mock'

Benchmark.bm(10000) do |x|
  x.report :mocha do
    array = [1]
    array.expects(:push).with(2).returns([1, 2])
    array.push(2)
  end
  x.report :delegator do
    array = [1]
    mock  = Class.new(SimpleDelegator) { def push(*args); [1, 2]; end }.new(array)
    mock.push(2)
  end
  x.report :simple_mock do
    array = [1]
    mock  = SimpleMock.new(array).expect(:push, [1, 2], [2])
    mock.push(2)
  end
end

benchmark.txt

                  user       system     total      real
mocha:            0.000000   0.000000   0.000000   (0.000279)
simple_delegator: 0.000000   0.000000   0.000000   (0.000029)
simple_mock:      0.000000   0.000000   0.000000   (0.000057)

I couldn't get Benchmark.bm to work like that. As far as I could tell, the argument to bm is the label width. It no effect in getting the tests to run multiple times for me. See my fork to see what did work.