def assertNoNRTLeak(self):
        """
        A context manager that asserts no NRT leak was created during
        the execution of the enclosed block.
        """
        old = rtsys.get_allocation_stats()
        yield
        new = rtsys.get_allocation_stats()
        total_alloc = new.alloc - old.alloc
        total_free = new.free - old.free
        total_mi_alloc = new.mi_alloc - old.mi_alloc
        total_mi_free = new.mi_free - old.mi_free
        self.assertEqual(total_alloc, total_free,
                         "number of data allocs != number of data frees")
        self.assertEqual(total_mi_alloc, total_mi_free,
                         "number of meminfo allocs != number of meminfo frees")

        A context manager that asserts no NRT leak was created during
        the execution of the enclosed block.
        
numba/tests/support.py