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.

1 files changed, 10 insertions, 1 deletions

diff --git a/lib/tasks/spec.rake b/lib/tasks/spec.rake
index 831746815d7..3ae5c250694 100644
--- a/lib/tasks/spec.rake
+++ b/lib/tasks/spec.rake
@@ -19,11 +19,20 @@ namespace :spec do
     run_commands(cmds)
   end
 
+  desc 'GitLab | Rspec | Run benchmark specs'
+  task :benchmark do
+    cmds = [
+      %W(rake gitlab:setup),
+      %W(rspec spec --tag @benchmark)
+    ]
+    run_commands(cmds)
+  end
+
   desc 'GitLab | Rspec | Run other specs'
   task :other do
     cmds = [
       %W(rake gitlab:setup),
-      %W(rspec spec --tag ~@api --tag ~@feature)
+      %W(rspec spec --tag ~@api --tag ~@feature --tag ~@benchmark)
     ]
     run_commands(cmds)
   end