Add py3k warnings for object, type, cell and dict comparisons. This should resolve issue2342 and partly resolve issue2373.

Lib/test/test_py3kwarn.py

@@ -0,0 +1,60 @@
+import unittest
+from test.test_support import catch_warning, TestSkipped, run_unittest
+import warnings
+
+# TODO: This is a hack to raise TestSkipped if -3 is not enabled. Instead
+# of relying on callable to have a warning, we should expose the -3 flag
+# to Python code somehow
+with catch_warning() as w:
+    callable(int)
+    if w.message is None:
+        raise TestSkipped('%s must be run with the -3 flag' % __name__)
+
+class TestPy3KWarnings(unittest.TestCase):
+
+    def test_type_inequality_comparisons(self):
+        expected = 'type inequality comparisons not supported in 3.x.'
+        with catch_warning() as w:
+            self.assertWarning(int < str, w, expected)
+        with catch_warning() as w:
+            self.assertWarning(type < object, w, expected)
+
+    def test_object_inequality_comparisons(self):
+        expected = 'comparing unequal types not supported in 3.x.'
+        with catch_warning() as w:
+            self.assertWarning(str < [], w, expected)
+        with catch_warning() as w:
+            self.assertWarning(object() < (1, 2), w, expected)
+
+    def test_dict_inequality_comparisons(self):
+        expected = 'dict inequality comparisons not supported in 3.x.'
+        with catch_warning() as w:
+            self.assertWarning({} < {2:3}, w, expected)
+        with catch_warning() as w:
+            self.assertWarning({} <= {}, w, expected)
+        with catch_warning() as w:
+            self.assertWarning({} > {2:3}, w, expected)
+        with catch_warning() as w:
+            self.assertWarning({2:3} >= {}, w, expected)
+
+    def test_cell_inequality_comparisons(self):
+        expected = 'cell comparisons not supported in 3.x.'
+        def f(x):
+            def g():
+                return x
+            return g
+        cell0, = f(0).func_closure
+        cell1, = f(1).func_closure
+        with catch_warning() as w:
+            self.assertWarning(cell0 == cell1, w, expected)
+        with catch_warning() as w:
+            self.assertWarning(cell0 < cell1, w, expected)
+
+    def assertWarning(self, _, warning, expected_message):
+        self.assertEqual(str(warning.message), expected_message)
+
+def test_main():
+    run_unittest(TestPy3KWarnings)
+
+if __name__ == '__main__':
+    test_main()