This class method can be used in "describe" blocks to specify the
subject of a benchmark. This lets you write:
benchmark_subject { Foo }
instead of:
benchmark_subject { -> { Foo } }
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.
Rémy Coutable