Skip tests on python implementations without getrefcount()

PyPy is one of these.

tests/test_cursor.py

@@ -27,7 +27,7 @@ import psycopg2
 import psycopg2.extensions
 from psycopg2.extensions import b
 from testutils import unittest, ConnectingTestCase, skip_before_postgres
-from testutils import skip_if_no_namedtuple
+from testutils import skip_if_no_namedtuple, skip_if_no_getrefcount
 
 class CursorTests(ConnectingTestCase):
 
@@ -97,6 +97,7 @@ class CursorTests(ConnectingTestCase):
         self.assertEqual(b('SELECT 10.3;'),
             cur.mogrify("SELECT %s;", (Decimal("10.3"),)))
 
+    @skip_if_no_getrefcount
     def test_mogrify_leak_on_multiple_reference(self):
         # issue #81: reference leak when a parameter value is referenced
         # more than once from a dict.
@@ -157,6 +158,7 @@ class CursorTests(ConnectingTestCase):
         curs = self.conn.cursor()
         w = ref(curs)
         del curs
+        import gc; gc.collect()
         self.assert_(w() is None)
 
     def test_null_name(self):

tests/test_module.py

@@ -199,7 +199,7 @@ class ExceptionsTestCase(ConnectingTestCase):
         self.assertEqual(diag.sqlstate, '42P01')
 
         del diag
-        gc.collect()
+        gc.collect(); gc.collect()
         assert(w() is None)
 
     @skip_copy_if_green

tests/testutils.py

@@ -293,6 +293,15 @@ def skip_if_green(reason):
 
 skip_copy_if_green = skip_if_green("copy in async mode currently not supported")
 
+def skip_if_no_getrefcount(f):
+    @wraps(f)
+    def skip_if_no_getrefcount_(self):
+        if not hasattr(sys, 'getrefcount'):
+            return self.skipTest('skipped, no sys.getrefcount()')
+        else:
+            return f(self)
+    return skip_if_no_getrefcount_
+
 def script_to_py3(script):
     """Convert a script to Python3 syntax if required."""
     if sys.version_info[0] < 3: