add `__reversed__()`

tests/tests_tqdm.py

@@ -1975,6 +1975,16 @@ def test_closed():
                 our_file.close()
 
 
+def test_reversed(capsys):
+    """Test reversed()"""
+    for _ in reversed(tqdm(_range(9))):
+        pass
+    out, err = capsys.readouterr()
+    assert not out
+    assert '  0%' in err
+    assert '100%' in err
+
+
 def test_contains(capsys):
     """Test __contains__ doesn't iterate"""
     with tqdm(_range(9)) as t:

tqdm/std.py

@@ -1131,6 +1131,17 @@ class tqdm(Comparable):
             else self.iterable.__length_hint__() if hasattr(self.iterable, "__length_hint__")
             else getattr(self, "total", None))
 
+    def __reversed__(self):
+        try:
+            orig = self.iterable
+        except AttributeError:
+            raise TypeError("'tqdm' object is not reversible")
+        else:
+            self.iterable = reversed(self.iterable)
+            return self.__iter__()
+        finally:
+            self.iterable = orig
+
     def __contains__(self, item):
         contains = getattr(self.iterable, '__contains__', None)
         return contains(item) if contains is not None else item in self.__iter__()