Today I could run CPython unittests on top of PyPy. test_call is passed. :-) Some problems: 1) For some reason, test_support complains if not imported from test package. Error message is: ImportError: test_support must be imported from the test package 2) PyPy's sys.path includes appspace/ and interpreter/. And they have their own test/ subdirectory, thus breaking import from test package. 3) PyPy methods have no __doc__. CPython methods always have __doc__, even if it is None. This confuses unittest: try: self.__testMethodName = methodName testMethod = getattr(self, methodName) self.__testMethodDoc = testMethod.__doc__ except AttributeError: raise ValueError # ... testMethod.__doc__ never raises AttributeError in CPython. So this error is wrongly reported as missing test method, not test method docstring. I just wanted to run CPython unittests on PyPy, without fixing these glitches. Here are workarounds: 1) mv appspace/test appspace/xtest 2) mv interpreter/test interpreter/xtest 3) cp /usr/lib/python2.3/unittest.py appspace 4) Patch unittest.py: --- unittest.py.orig 2004-07-14 21:19:19.000000000 +0900 +++ unittest.py 2004-07-14 21:19:29.000000000 +0900 @@ -169,7 +169,7 @@ try: self.__testMethodName = methodName testMethod = getattr(self, methodName) - self.__testMethodDoc = testMethod.__doc__ + self.__testMethodDoc = None # testMethod.__doc__ except AttributeError: raise ValueError, "no such test method in %s: %s" % \ (self.__class__, methodName) 5) Copy CPython Lib/test to work directory. 6) pypy test/test_call.py You will see "Ran 27 tests in 22.790s". CPython reports "Ran 27 tests in 0.008s". That gives 3500x slow performance. Well, that was expected. Happy hacking,