Avoid triggering fetch for all hidden attributes

CHANGES.rst

@@ -1,6 +1,14 @@
 Change Log
 ==========
 
+Unreleased
+----------
+
+**Fixed**
+
+* Fix bug where ipython tries to access attribute
+  ``_ipython_canary_method_should_not_exist_`` resulting in a useless fetch.
+
 4.0.0rc3 (2016/11/26)
 ---------------------
 

praw/models/reddit/base.py

@@ -27,7 +27,7 @@ def __eq__(self, other):
 
     def __getattr__(self, attribute):
         """Return the value of `attrribute`."""
-        if not attribute.startswith('__') and not self._fetched:
+        if not attribute.startswith('_') and not self._fetched:
             self._fetch()
             return getattr(self, attribute)
         raise AttributeError('{!r} object has no attribute {!r}'

tests/unit/models/reddit/test_comment.py

@@ -54,3 +54,9 @@ def test_repr(self):
     def test_str(self):
         comment = Comment(self.reddit, _data={'id': 'dummy'})
         assert str(comment) == 'dummy'
+
+    def test_unset_hidden_attribute_does_not_fetch(self):
+        comment = Comment(self.reddit, _data={'id': 'dummy'})
+        with pytest.raises(AttributeError):
+            comment._ipython_canary_method_should_not_exist_
+        assert not comment._fetched