DEPR: provide deprecations and exposure for NaTType

xref #16137

Author: jreback

pandas/__init__.py

@@ -77,6 +77,7 @@
                           moved={'Timestamp': 'pandas.Timestamp',
                                  'Timedelta': 'pandas.Timedelta',
                                  'NaT': 'pandas.NaT',
+                                 'NaTType': 'pandas.api.types.NaTType',
                                  'OutOfBoundsDatetime': 'pandas.errors.OutOfBoundsDatetime'})
 
 # use the closest tagged version if possible

pandas/api/types/__init__.py

@@ -7,4 +7,6 @@
                                        IntervalDtype)
 from pandas.core.dtypes.concat import union_categoricals  # noqa
 from pandas._libs.lib import infer_dtype  # noqa
+from pandas._libs.tslib import NaTType  # noqa
+
 del np  # noqa

pandas/tests/api/test_types.py

@@ -34,7 +34,7 @@ class TestTypes(Base, tm.TestCase):
                'is_named_tuple', 'is_sequence',
                'pandas_dtype', 'union_categoricals', 'infer_dtype']
     dtypes = ['CategoricalDtype', 'DatetimeTZDtype',
-              'PeriodDtype', 'IntervalDtype']
+              'PeriodDtype', 'IntervalDtype', 'NaTType']
 
     def test_types(self):
 
@@ -93,3 +93,10 @@ def test_moved_infer_dtype():
     with catch_warnings(record=True):
         e = pandas.lib.infer_dtype('foo')
         assert e is not None
+
+
+def test_moved_NaTType():
+
+    with catch_warnings(record=True):
+        t = pandas.tslib.NaTType
+        assert t is not None

pandas/tslib.py

@@ -4,4 +4,4 @@
 warnings.warn("The pandas.tslib module is deprecated and will be "
               "removed in a future version.", FutureWarning, stacklevel=2)
 from pandas._libs.tslib import (Timestamp, Timedelta,
-                               NaT, OutOfBoundsDatetime)
+                               NaT, NaTType, OutOfBoundsDatetime)