rspec users - Jan 2011 - Performance tests using Rspec

1) Know of any guides to writing performance tests using Rspec?

2) Does Rspec have the capability to run specs in benchmarking or
profiling mode similar to the way Rails has performance tests that run
in these modes (http://guides.rubyonrails.org/
performance_testing.html)?

On Jan 16, 2011, at 8:29 PM, Evan wrote:
> 1) Know of any guides to writing performance tests using Rspec?
There''s nothing built in as of yet, but you can do this pretty easily:

<code>
require ''benchmark''

RSpec::Matchers.define :take_less_than do |n|
  chain :seconds do; end
  
  match do |block|
    @elapsed = Benchmark.realtime do
      block.call
    end
    @elapsed <= n
  end

end

describe "addition" do
  it "runs fast" do
    expect do
      10000.times { 1 + 2 }
    end.to take_less_than(0.001).seconds
  end
end
</code>
> 2) Does Rspec have the capability to run specs in benchmarking or
> profiling mode similar to the way Rails has performance tests that run
> in these modes (http://guides.rubyonrails.org/
> performance_testing.html)?
There is a --profile command line switch:

  rspec spec --profile

which gives you the 10 slowest running examples, but that includes time to run
all the before, after, and around hooks as well. My guess is you''d be
better off with the matcher above.

HTH,
David

A while ago, I was looking at Minitest''s benchmarking capabilities 
(contained in a single file
here<https://github.com/seattlerb/minitest/blob/master/lib/minitest/benchmark.rb>)
and I thought it would be great to have an equivalent in RSpec. They have 
methods to assert type of performance (linear, exponential...) of a given 
block. Looking at minitest''s file it might be relatively trivial to 
implement, but the question is: do you think that would naturally fit in 
rspec-matchers, or in a separate rspec-benchmark gem/plugin?
Personally I think it''s a good piece of functionality and deserves
being
baked in RSpec, but I''m not sure if many people would actually use it. 
Thoughts? 
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On Jan 26, 2011, at 4:06 AM, Josep M. Bach wrote:
> A while ago, I was looking at Minitest''s benchmarking capabilities
(contained in a single file here) and I thought it would be great to have an
equivalent in RSpec. They have methods to assert type of performance (linear,
exponential...) of a given block. Looking at minitest''s file it might
be relatively trivial to implement, but the question is: do you think that would
naturally fit in rspec-matchers, or in a separate rspec-benchmark gem/plugin?
> Personally I think it''s a good piece of functionality and deserves
being baked in RSpec, but I''m not sure if many people would actually
use it. Thoughts?
I''d like to see it in an extension gem first. We can always merge it in
if it becomes a standard component. If not, it''s just more stuff to
maintain that nobody uses :)
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