Basic setup for an RSpec based benchmark suitebenchmark-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, 40 insertions, 0 deletions

diff --git a/spec/benchmarks/models/user_spec.rb b/spec/benchmarks/models/user_spec.rb
new file mode 100644
index 00000000000..a08c84ffce4
--- /dev/null
+++ b/spec/benchmarks/models/user_spec.rb
@@ -0,0 +1,40 @@
+require 'spec_helper'
+
+describe User, benchmark: true do
+  describe '.by_login' do
+    before do
+      %w{Alice Bob Eve}.each do |name|
+        create(:user,
+               email: "#{name}@gitlab.com",
+               username: name,
+               name: name)
+      end
+    end
+
+    let(:iterations) { 1000 }
+
+    describe 'using a capitalized username' do
+      subject { -> { User.by_login('Alice') } }
+
+      it { is_expected.to iterate_per_second(iterations) }
+    end
+
+    describe 'using a lowercase username' do
+      subject { -> { User.by_login('alice') } }
+
+      it { is_expected.to iterate_per_second(iterations) }
+    end
+
+    describe 'using a capitalized Email address' do
+      subject { -> { User.by_login('Alice@gitlab.com') } }
+
+      it { is_expected.to iterate_per_second(iterations) }
+    end
+
+    describe 'using a lowercase Email address' do
+      subject { -> { User.by_login('alice@gitlab.com') } }
+
+      it { is_expected.to iterate_per_second(iterations) }
+    end
+  end
+end