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module BenchmarkMatchers
extend RSpec::Matchers::DSL
def self.included(into)
into.extend(ClassMethods)
end
matcher :iterate_per_second do |min_iterations|
supports_block_expectations
match do |block|
@max_stddev ||= 30
@entry = benchmark(&block)
expect(@entry.ips).to be >= min_iterations
expect(@entry.stddev_percentage).to be <= @max_stddev
end
chain :with_maximum_stddev do |value|
@max_stddev = value
end
description do
"run at least #{min_iterations} iterations per second"
end
failure_message do
ips = @entry.ips.round(2)
stddev = @entry.stddev_percentage.round(2)
"expected at least #{min_iterations} iterations per second " \
"with a maximum stddev of #{@max_stddev}%, instead of " \
"#{ips} iterations per second with a stddev of #{stddev}%"
end
end
# Benchmarks the given block and returns a Benchmark::IPS::Report::Entry.
def benchmark(&block)
report = Benchmark.ips(quiet: true) do |bench|
bench.report do
instance_eval(&block)
end
end
report.entries[0]
end
module ClassMethods
# Wraps around rspec's subject method so you can write:
#
# benchmark_subject { SomeClass.some_method }
#
# instead of:
#
# subject { -> { SomeClass.some_method } }
def benchmark_subject(&block)
subject { block }
end
end
end