'start method in the ``RequestLoadScenario`` throws a
``RequestScenarioAlreadyStarted`` if the scenario is already started.'

@capture_logging(None)
def test_scenario_throws_exception_when_already_started(self, _logger):

    c = Clock()
    cluster = self.make_cluster(self.get_fake_flocker_client_instance())
    sample_size = 5
    s = write_request_load_scenario(c, cluster, sample_size=sample_size)
    s.start()
    c.pump(repeat(1, sample_size))
    self.assertRaises(RequestScenarioAlreadyStarted, s.start)
