diff --git a/test/python/utilities.py b/test/python/utilities.py
index 4bc1f7168..004090396 100644
--- a/test/python/utilities.py
+++ b/test/python/utilities.py
@@ -1,4 +1,15 @@
 import numpy as np
+import unittest
+
+class CanteraTest(unittest.TestCase):
+    def assertNear(self, a, b, rtol=1e-8, atol=1e-12, msg=None):
+        cmp = 2 * abs(a - b)/(abs(a) + abs(b) + atol)
+        if cmp > rtol:
+            message = ('AssertNear: %.14g - %.14g = %.14g\n' % (a, b, a-b) +
+                       'Relative error of %10e exceeds rtol = %10e' % (cmp, rtol))
+            if msg:
+                message = msg + '\n' + message
+            self.fail(message)
 
 def compareTimeSeries(reference, sample, rtol=1e-5, atol=1e-12):
     """