pyximport for test helper cython extensions

Allows cython extension to be built for unit tests without having it in
the setup.

setup.py

@@ -273,7 +273,6 @@ if "--no-cython" not in sys.argv and not os.environ.get('CASS_DRIVER_NO_CYTHON')
                 for m in cython_candidates],
             exclude_failures=True))
         extensions.extend(cythonize("cassandra/*.pyx"))
-        extensions.extend(cythonize("tests/unit/cython/*.pyx"))
     except Exception:
         sys.stderr.write("Cython is not installed. Not compiling core driver files as extensions (optional).")
 

tests/unit/cython/utils.py

@@ -14,6 +14,10 @@
 
 from cassandra.cython_deps import HAVE_CYTHON, HAVE_NUMPY
 
+if HAVE_CYTHON:
+    import pyximport
+    pyximport.install()
+
 try:
     import unittest2 as unittest
 except ImportError:

tox.ini

@@ -11,6 +11,7 @@ deps = nose
 deps = {[base]deps}
        sure
        blist
+       cython
        py26: unittest2
        py{26,27}: gevent
        twisted