diff --git a/numba_cuda/numba/cuda/simulator/memory_management/nrt.py b/numba_cuda/numba/cuda/simulator/memory_management/nrt.py
index 87e8407dd..b62907cf9 100644
--- a/numba_cuda/numba/cuda/simulator/memory_management/nrt.py
+++ b/numba_cuda/numba/cuda/simulator/memory_management/nrt.py
@@ -3,7 +3,19 @@
 
 from numba import config
 
-rtsys = None
+
+class RTSys:
+    def __init__(self, *args, **kwargs):
+        pass
+
+    def memsys_enable_stats(self):
+        pass
+
+    def get_allocation_stats(self):
+        pass
+
+
+rtsys = RTSys()
 
 config.CUDA_NRT_STATS = False
 config.CUDA_ENABLE_NRT = False
diff --git a/numba_cuda/numba/cuda/tests/__init__.py b/numba_cuda/numba/cuda/tests/__init__.py
index feb74ca8b..c436d765c 100644
--- a/numba_cuda/numba/cuda/tests/__init__.py
+++ b/numba_cuda/numba/cuda/tests/__init__.py
@@ -2,7 +2,7 @@
 # SPDX-License-Identifier: BSD-2-Clause
 
 from fnmatch import fnmatch
-from numba.testing import unittest
+import unittest
 from numba import cuda
 from os.path import dirname, isfile, join, normpath, relpath, splitext
 
diff --git a/numba_cuda/numba/cuda/tests/cudapy/test_debuginfo.py b/numba_cuda/numba/cuda/tests/cudapy/test_debuginfo.py
index f96fe424b..87fe592bf 100644
--- a/numba_cuda/numba/cuda/tests/cudapy/test_debuginfo.py
+++ b/numba_cuda/numba/cuda/tests/cudapy/test_debuginfo.py
@@ -14,7 +14,7 @@
 import unittest
 import warnings
 from numba.core.errors import NumbaDebugInfoWarning
-from numba.tests.support import ignore_internal_warnings
+from numba.cuda.tests.support import ignore_internal_warnings
 import numpy as np
 import inspect
 
diff --git a/numba_cuda/numba/cuda/tests/cudapy/test_ssa.py b/numba_cuda/numba/cuda/tests/cudapy/test_ssa.py
index a6b39d77f..ec78bcedb 100644
--- a/numba_cuda/numba/cuda/tests/cudapy/test_ssa.py
+++ b/numba_cuda/numba/cuda/tests/cudapy/test_ssa.py
@@ -15,7 +15,7 @@
 from numba.core import errors
 
 from numba.extending import overload
-from numba.tests.support import override_config
+from numba.cuda.tests.support import override_config
 from numba.cuda.testing import CUDATestCase, skip_on_cudasim
 
 
diff --git a/numba_cuda/numba/cuda/tests/cudapy/test_ufuncs.py b/numba_cuda/numba/cuda/tests/cudapy/test_ufuncs.py
index 8d11e0005..a455e0b2e 100644
--- a/numba_cuda/numba/cuda/tests/cudapy/test_ufuncs.py
+++ b/numba_cuda/numba/cuda/tests/cudapy/test_ufuncs.py
@@ -9,7 +9,7 @@
 from numba import config, cuda, types, njit, typeof
 from numba.np import numpy_support
 from numba.cuda.tests.support import TestCase
-from numba.tests.support import MemoryLeakMixin
+from numba.cuda.tests.support import MemoryLeakMixin
 
 
 class BaseUFuncTest(MemoryLeakMixin):
diff --git a/numba_cuda/numba/cuda/tests/cudapy/test_vectorize_decor.py b/numba_cuda/numba/cuda/tests/cudapy/test_vectorize_decor.py
index 2f977589c..d37332158 100644
--- a/numba_cuda/numba/cuda/tests/cudapy/test_vectorize_decor.py
+++ b/numba_cuda/numba/cuda/tests/cudapy/test_vectorize_decor.py
@@ -6,7 +6,7 @@
 
 from numba import vectorize, cuda, int32, uint32, float32, float64
 from numba.cuda.testing import skip_on_cudasim, CUDATestCase
-from numba.tests.support import CheckWarningsMixin
+from numba.cuda.tests.support import CheckWarningsMixin
 
 import unittest
 
diff --git a/numba_cuda/numba/cuda/tests/support.py b/numba_cuda/numba/cuda/tests/support.py
index 2e08e1816..7b2dfedc7 100644
--- a/numba_cuda/numba/cuda/tests/support.py
+++ b/numba_cuda/numba/cuda/tests/support.py
@@ -764,3 +764,56 @@ def skip_if_no_external_compiler(self):
 
         if not external_compiler_works():
             self.skipTest("No suitable external compiler was found.")
+
+
+class MemoryLeak(object):
+    __enable_leak_check = True
+
+    def memory_leak_setup(self):
+        # Clean up any NRT-backed objects hanging in a dead reference cycle
+        gc.collect()
+        self.__init_stats = rtsys.get_allocation_stats()
+
+    def memory_leak_teardown(self):
+        if self.__enable_leak_check:
+            self.assert_no_memory_leak()
+
+    def assert_no_memory_leak(self):
+        old = self.__init_stats
+        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)
+        self.assertEqual(total_mi_alloc, total_mi_free)
+
+    def disable_leak_check(self):
+        # For per-test use when MemoryLeakMixin is injected into a TestCase
+        self.__enable_leak_check = False
+
+
+class MemoryLeakMixin(EnableNRTStatsMixin, MemoryLeak):
+    def setUp(self):
+        super(MemoryLeakMixin, self).setUp()
+        self.memory_leak_setup()
+
+    def tearDown(self):
+        gc.collect()
+        self.memory_leak_teardown()
+        super(MemoryLeakMixin, self).tearDown()
+
+
+class CheckWarningsMixin(object):
+    @contextlib.contextmanager
+    def check_warnings(self, messages, category=RuntimeWarning):
+        with warnings.catch_warnings(record=True) as catch:
+            warnings.simplefilter("always")
+            yield
+        found = 0
+        for w in catch:
+            for m in messages:
+                if m in str(w.message):
+                    self.assertEqual(w.category, category)
+                    found += 1
+        self.assertEqual(found, len(messages))