COMPAT: Catch warnings on tab-complete in IPy 6

Properties may run code with Jedi completion in IPython 6

Closes #16409

Author: TomAugspurger

doc/source/whatsnew/v0.20.2.txt

@@ -38,6 +38,10 @@ Bug Fixes
 
 - Bug in using ``pathlib.Path`` or ``py.path.local`` objects with io functions (:issue:`16291`)
 
+
+- Fixed a compatibility issue with IPython 6.0's tab completion showing deprecation warnings on Categoricals (:issue:`16409`)
+
+
 Conversion
 ^^^^^^^^^^
 

pandas/conftest.py

@@ -45,3 +45,13 @@ def spmatrix(request):
     tm._skip_if_no_scipy()
     from scipy import sparse
     return getattr(sparse, request.param + '_matrix')
+
+
+@pytest.fixture
+def ip():
+    """An instance of IPython.InteractiveShell.
+    Will raise a skip if IPython is not installed.
+    """
+    pytest.importorskip('IPython', minversion="6.0.0")
+    from IPython.core.interactiveshell import InteractiveShell
+    return InteractiveShell()

pandas/core/categorical.py

@@ -342,6 +342,13 @@ def __init__(self, values, categories=None, ordered=False, fastpath=False):
         self._categories = categories
         self._codes = coerce_indexer_dtype(codes, categories)
 
+    def __dir__(self):
+        # Avoid IPython warnings for deprecated properties
+        # https://github.com/pandas-dev/pandas/issues/16409
+        rv = set(dir(type(self)))
+        rv.discard("labels")
+        return sorted(rv)
+
     @property
     def _constructor(self):
         return Categorical

pandas/tests/test_categorical.py

@@ -736,6 +736,20 @@ def test_unicode_print(self):
 
             assert _rep(c) == expected
 
+    def test_tab_complete_warning(self, ip):
+        # https://github.com/pandas-dev/pandas/issues/16409
+        pytest.importorskip('IPython', minversion="6.0.0")
+        from IPython.core.interactiveshell import InteractiveShell
+        from IPython.core.completer import provisionalcompleter
+
+        code = "import pandas as pd; c = pd.Categorical([])"
+        ip.run_code(code)
+        with pytest.warns(None) as record:
+            with provisionalcompleter('ignore'):
+                list(ip.Completer.completions('c.', 1))
+
+        assert len(record) == 0
+
     def test_periodindex(self):
         idx1 = PeriodIndex(['2014-01', '2014-01', '2014-02', '2014-02',
                             '2014-03', '2014-03'], freq='M')

pandas/tests/test_resample.py

@@ -3,6 +3,7 @@
 from warnings import catch_warnings
 from datetime import datetime, timedelta
 from functools import partial
+from textwrap import dedent
 
 import pytz
 import pytest
@@ -2816,6 +2817,21 @@ def test_back_compat_v180(self):
             expected = df.groupby('A').resample('4s').mean().ffill()
             assert_frame_equal(result, expected)
 
+    @pytest.mark.xfail
+    def test_tab_complete_ipython6(self, ip):
+        from IPython.core.completer import provisionalcompleter
+        code = dedent("""\
+        import pandas.util.testing as tm
+        s = tm.makeTimeSeries()
+        rs = s.resample("D")
+        """)
+        ip.run_code(code)
+
+        with pytest.warns(None) as record:
+            with provisionalcompleter('ignore'):
+                list(ip.Completer.completions('rs.', 1))
+        assert len(record) == 0
+
     def test_deferred_with_groupby(self):
 
         # GH 12486