add test

Author: jorisvandenbossche

pandas/_libs/properties.pyx

@@ -17,8 +17,11 @@ cdef class CachedProperty(object):
  self.__doc__ = getattr(func, '__doc__', None)
 
  def __get__(self, obj, typ):
- # Get the cache or set a default one if needed
+ if obj is None:
+ # accessed on the class, not the instance
+ return self
 
+ # Get the cache or set a default one if needed
  cache = getattr(obj, '_cache', None)
  if cache is None:
  try:

pandas/tests/test_lib.py

@@ -3,6 +3,7 @@
 import pytest
 
 import numpy as np
+from pandas import Index
 from pandas._libs import lib, writers as libwriters
 import pandas.util.testing as tm
 
@@ -198,3 +199,8 @@ def test_get_reverse_indexer(self):
  result = lib.get_reverse_indexer(indexer, 5)
  expected = np.array([4, 2, 3, 6, 7], dtype=np.int64)
  tm.assert_numpy_array_equal(result, expected)
+
+
+def test_cache_readonly_preserve_docstrings():
+ # GH18197
+ assert Index.hasnans.__doc__ is not None