1 files changed, 84 insertions, 0 deletions
diff --git a/tests/functional/b/bad_reversed_sequence.py b/tests/functional/b/bad_reversed_sequence.py
new file mode 100644
index 000000000..6cfac5bed
--- /dev/null
+++ b/tests/functional/b/bad_reversed_sequence.py
@@ -0,0 +1,84 @@
+""" Checks that reversed() receive proper argument """
+# pylint: disable=missing-docstring, useless-object-inheritance
+# pylint: disable=too-few-public-methods,no-self-use,no-absolute-import
+from collections import deque
+
+__revision__ = 0
+
+class GoodReversed(object):
+    """ Implements __reversed__ """
+    def __reversed__(self):
+        return [1, 2, 3]
+
+class SecondGoodReversed(object):
+    """ Implements __len__ and __getitem__ """
+    def __len__(self):
+        return 3
+
+    def __getitem__(self, index):
+        return index
+
+class BadReversed(object):
+    """ implements only len() """
+    def __len__(self):
+        return 3
+
+class SecondBadReversed(object):
+    """ implements only __getitem__ """
+    def __getitem__(self, index):
+        return index
+
+class ThirdBadReversed(dict):
+    """ dict subclass """
+
+def uninferable(seq):
+    """ This can't be infered at this moment,
+    make sure we don't have a false positive.
+    """
+    return reversed(seq)
+
+def test(path):
+    """ test function """
+    seq = reversed() # No argument given
+    seq = reversed(None) # [bad-reversed-sequence]
+    seq = reversed([1, 2, 3])
+    seq = reversed((1, 2, 3))
+    seq = reversed(set()) # [bad-reversed-sequence]
+    seq = reversed({'a': 1, 'b': 2}) # [bad-reversed-sequence]
+    seq = reversed(iter([1, 2, 3])) # [bad-reversed-sequence]
+    seq = reversed(GoodReversed())
+    seq = reversed(SecondGoodReversed())
+    seq = reversed(BadReversed()) # [bad-reversed-sequence]
+    seq = reversed(SecondBadReversed()) # [bad-reversed-sequence]
+    seq = reversed(range(100))
+    seq = reversed(ThirdBadReversed()) # [bad-reversed-sequence]
+    seq = reversed(lambda: None) # [bad-reversed-sequence]
+    seq = reversed(deque([]))
+    seq = reversed("123")
+    seq = uninferable([1, 2, 3])
+    seq = reversed(path.split("/"))
+    return seq
+
+def test_dict_ancestor_and_reversed():
+    """Don't emit for subclasses of dict, with __reversed__ implemented."""
+    from collections import OrderedDict
+
+    class Child(dict):
+        def __reversed__(self):
+            return reversed(range(10))
+
+    seq = reversed(OrderedDict())
+    return reversed(Child()), seq
+
+
+def test_dont_emit_for_reversing_enums():
+    """Don't emit when reversing enum classes"""
+    from enum import IntEnum
+
+    class Color(IntEnum):
+        RED = 1
+        GREEN = 2
+        BLUE = 3
+
+    for color in reversed(Color):
+        yield color