wait while &block returns true

wait_while.rb

# Public: Wait while block returns false by repeatedly calling the block until
# it returns true.
#
# Useful to wait for external systems to do something. Like launching daemons
# in integration tests. Which you're not actually doing right? >_<
#
# timeout        - Integer specifying how many seconds to wait for.
# retry_interval - Interval in seconds between calling block while it's
#                - returning false.
# block          - A block which returns true or false. It should only return
#                  true when there no need to wait any more.
#
# Returns false if timeout reached before block returned true, otherwise it
# returns true.
def wait_while(timeout = 2, retry_interval = 0.1, &block)
  start = Time.now
  while (result = !!block.call)
    break if (Time.now - start).to_i >= timeout
    sleep(retry_interval)
  end
  !result
end