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eventually helper method for making assertions against asynchronous systems
# usage:
# it "should return a result of 5" do
# eventually { long_running_thing.result.should eq(5) }
# end
module AsyncHelper
def eventually(:options = {})
timeout = options[:timeout] || 2
interval = options[:interval] || 0.1
time_limit = + timeout
loop do
rescue => error
return if error.nil?
raise error if >= time_limit
sleep interval
# Can we put this into RSpec somewhere?

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@aslakhellesoy aslakhellesoy commented Sep 20, 2011

Wouldn't this peg the CPU and possibly starve the thing you're waiting for?


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@mattwynne mattwynne commented Sep 20, 2011

Good point. Needs to take a nap in the loop. Updated.


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@mitchlloyd mitchlloyd commented Oct 4, 2013

@mattwynne Looks like there is a syntax error on line 6 with the colon.


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@xam7247 xam7247 commented Aug 10, 2015

Stumbled across this, and realised that the gist no more works since rspec expectation failure now subclasses from Exception rather than StandardError (rspec/rspec-expectations@eafa55d#diff-f14d34de26325e61579baa36128c97cb)

Here's a fork that rescues both StandardError and RSpec::Expectations::ExpectationNotMetError:

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