Fix Issue #21336: Defeault behavior for resolution property in Timestamps

doc/source/whatsnew/v0.23.1.txt

@@ -131,3 +131,5 @@ Bug Fixes
 **Other**
 
 - Tab completion on :class:`Index` in IPython no longer outputs deprecation warnings (:issue:`21125`)
+- Bug preventing pandas from being importable with -OO optimization (:issue:`21071`)
+- Timestamp resolution returns a :class:`Timedelta` (in nanoseconds) rather than a normal `timedelta` object (in microseconds) (:issue:`21336`)

pandas/_libs/tslibs/timestamps.pyx

@@ -400,12 +400,17 @@ cdef class _Timestamp(datetime):
     def asm8(self):
         return np.datetime64(self.value, 'ns')
 
+    @property
+    def resolution(self):
+        """ Return resolution in a native pandas format. """
+        # GH 21336
+        return Timedelta(nanoseconds=1)
+
     def timestamp(self):
         """Return POSIX timestamp as float."""
         # py27 compat, see GH#17329
         return round(self.value / 1e9, 6)
 
-
 # ----------------------------------------------------------------------
 
 # Python front end to C extension type _Timestamp

pandas/tests/scalar/timestamp/test_timestamp.py

@@ -172,6 +172,11 @@ def test_woy_boundary(self):
                                2005, 1, 1), (2005, 1, 2)]])
         assert (result == [52, 52, 53, 53]).all()
 
+    def test_resolution(self):
+        # GH 21336
+        dt = Timestamp('2100-01-01 00:00:00')
+        assert dt.resolution == Timedelta(nanoseconds=1)
+
 
 class TestTimestampConstructors(object):