From 19893a1c10e4e6dfbdb56ad78de1599b6c8f6981 Mon Sep 17 00:00:00 2001
From: Yorick Peterse <yorickpeterse@gmail.com>
Date: Fri, 2 Oct 2015 17:00:23 +0200
Subject: Basic setup for an RSpec based benchmark suite

This benchmark suite uses benchmark-ips
(https://github.com/evanphx/benchmark-ips) behind the scenes. Specs can
be turned into benchmark specs by setting "benchmark" to "true" in the
top-level describe block like so:

    describe SomeClass, benchmark: true do

    end

Writing benchmarks can be done using custom RSpec matchers, for example:

    describe MaruTheCat, benchmark: true do
      describe '#jump_in_box' do
        it 'should run 1000 iterations per second' do
          maru = described_class.new

          expect { maru.jump_in_box }.to iterate_per_second(1000)
        end
      end
    end

By default the "iterate_per_second" expectation requires a standard
deviation under 30% (this is just an arbitrary default for now). You can
change this by chaining "with_maximum_stddev" on the expectation:

    expect { maru.jump_in_box }.to iterate_per_second(1000)
      .with_maximum_stddev(10)

This will change the expectation to require a maximum deviation of 10%.

Alternatively you can use the it block style to write specs:

    describe MaruTheCat, benchmark: true do
      describe '#jump_in_box' do
        subject { -> { described_class.new } }

        it { is_expected.to iterate_per_second(1000) }
      end
    end

Because "iterate_per_second" operates on a block, opposed to a static
value, the "subject" method must return a Proc. This looks a bit goofy
but I have been unable to find a nice way around this.
---
 spec/spec_helper.rb | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

(limited to 'spec/spec_helper.rb')

diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index dfe855926c6..05bb32baa90 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -14,6 +14,7 @@ require File.expand_path("../../config/environment", __FILE__)
 require 'rspec/rails'
 require 'shoulda/matchers'
 require 'sidekiq/testing/inline'
+require 'benchmark/ips'
 
 # Requires supporting ruby files with custom matchers and macros, etc,
 # in spec/support/ and its subdirectories.
@@ -32,7 +33,7 @@ RSpec.configure do |config|
   config.include TestEnv
   config.include StubGitlabCalls
   config.include StubGitlabData
-
+  config.include BenchmarkMatchers, benchmark: true
 
   config.infer_spec_type_from_file_location!
   config.raise_errors_for_deprecations!
-- 
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