Design & Code

Performance Benchmarking Ruby with MiniTest

A handy feature of MiniTest is the performance benchmarking assertions. Here's an example testing a couple of methods that are constant and linear in time as a function of their inputs:

require 'rubygems'
require 'minitest/benchmark'
require 'minitest/autorun'

class Thing
  def constant_time_method(n)
    true # O(1)
  end
  
  def linear_time_method(n)
    n.times { |i| constant_time_method(i) } # O(n)
  end
end

class AwesomeTest < MiniTest::Unit::TestCase
  def setup
    @thing = Thing.new
  end
  
  def test_constant_time_method_performance
    assert_performance_constant 0.99999 do |n|
     @thing.constant_time_method(n)
    end
  end
  
  def test_linear_time_method_performance
    assert_performance_linear 0.9999 do |n|
      @thing.linear_time_method(n)
    end
  end
end

Whilst I wouldn't go nuts with this, it's a nice solution for when you have optimized some code and want to add a check against regressions.

Scope the source and docs for more details.