def test_should_pass_in_required_preexec(self, required_preexec, Popen):
		Popen.side_effect = self._fake_popen
		utils.run_shell('foo', create_process_group=True)

		Popen.assert_called_once()
		assert_call_got_kwargs(Popen, 0, preexec_fn=required_preexec.return_value)
	def test_preexec_fn_is_none_by_default(self, Popen):
		Popen.side_effect = self._fake_popen
		utils.run_shell('foo')

		Popen.assert_called_once()
		assert_call_got_kwargs(Popen, 0, preexec_fn=None)