test_helper.rb

# The data setup inside the block may take upto a second to be ready to pass the test. But probably much less.
def retrying_for(secconds = 1)
  limit = Time.now + secconds
  begin
    yield
  rescue
    if Time.now < limit
      sleep 0.05
      retry
    else
      raise
    end
  end
end

test_some_foo.rb

def test_should_update_via_queue
  @queue.push("Some foo")
  retrying_for(1.second) do # Data may not be updated right away, so give this test a second or so to run
    assert_equal 1, get_some_foo_count_via_api
  end
end