Mocha VS MiniTest::Mock and SimpleDelegate VS SimpleMock VS RR

benchmark.rb

require 'benchmark/ips'
require 'delegate'
require 'mocha/api'
require 'simple_mock'
require 'rr'

include Mocha::API
extend RR::Adapters::RRMethods

array = [1]

Benchmark.ips do |x|
  x.report 'mocha' do
    new_array = array.dup
    new_array.expects(:push).with(2).returns([1, 2])
    new_array.push(2)
  end

  x.report 'delegator' do
    mock  = Class.new(SimpleDelegator) { def push(*args); [1, 2]; end }.new(array)
    mock.push(2)
  end

  x.report 'simple_mock' do
    mock  = SimpleMock.new(array).expect(:push, [1, 2], [2])
    mock.push(2)
  end

  x.report 'rr' do
    new_array = array.dup
    mock(new_array).push(2) { [1, 2] }
    new_array.push(2)
  end
end

benchmark.txt

ruby 2.4.1p111 (2017-03-22 revision 58053) [x86_64-darwin16]

Warming up --------------------------------------
               mocha    99.000  i/100ms
           delegator    12.483k i/100ms
         simple_mock     5.741k i/100ms
                  rr   242.000  i/100ms
Calculating -------------------------------------
               mocha    315.303  (±16.2%) i/s -      1.584k in   5.143984s
           delegator    145.488k (±11.1%) i/s -    724.014k in   5.031831s
         simple_mock     61.882k (± 8.9%) i/s -    310.014k in   5.046684s
                  rr      2.507k (±15.4%) i/s -     12.342k in   5.082613s

Gemfile

# frozen_string_literal: true
source "https://rubygems.org"

gem "benchmark-ips"
gem "rr"
gem "mocha"
gem "simple_mock"

Gemfile.lock

GEM
  remote: https://rubygems.org/
  specs:
    benchmark-ips (2.7.2)
    metaclass (0.0.4)
    mocha (1.2.1)
      metaclass (~> 0.0.1)
    rr (1.2.0)
    simple_mock (0.0.2)

PLATFORMS
  ruby

DEPENDENCIES
  benchmark-ips
  mocha
  rr
  simple_mock

BUNDLED WITH
   1.15.0