mock_em

MockEM

MockEM provides the same interface as EM (a.k.a. EventMachine), but simulates the passage of time to execute your scheduled actions without delay. It is intended for use in tests.

Uses Timecop for simulating the passage of time.

Getting Started

You'll need to add require 'mock_em', as well as require 'timecop'.

At the beginning of your spec you can use the following snippet to mock EM within the scope of that spec.

# mock & restore EM
before(:all) do
  @logger = Logger.new(STDOUT)  # <-- Choose your own logger, as appropriate
    
  # Mock EM
  @orig_EM = EM
  EM = MockEM::MockEM.new(@logger, Timecop)
end
after(:all) do
  EM = @orig_EM
  Timecop.return
end

Any references to EM will then be using MockEM.

As a quick demonstration, the following code has a timer that would wait for 8 minutes with EM, but with MockEM it completes instantaneously:

require 'timecop'
require 'mock_em'
logger = Logger.new(STDOUT)
em = MockEM::MockEM.new(logger, Timecop)

em.run do
  em.add_timer(8 * 60) do
    puts "Done!"
    em.stop
  end
end    

Supported Features

MockEM supports many of the features of EM. Example of supported methods:

• Reactor: run, stop, reactor_running?
• Timers: next_tick, add_timer, add_periodic_timer, cancel_timer, get_max_timer_count
• Hooks: add_shutdown_hook, error_handler

Refer to mock_em_spec.rb for more details, as it runs the same set of specs against both MockEM and EM, to verify the behavior is identical.

Unsupported Features

Your mileage may vary.

Compatibility

Ruby 1.8.7 and above is supported.

Contributing

Pull requests welcome.

If you'd like to add missing functionality, you can use mock_em_spec.rb to verify that the behavior is identical in both MockEM and EM.

Contributors

• Jim Slattery
• Dominic Metzger

Maintained by the RightScale "Cornsilk_team"

License

MIT License, see LICENSE