TST: Added fromisocalendar test cases

doc/source/whatsnew/v1.0.0.rst

@@ -227,6 +227,7 @@ Other enhancements
 - Added new writer for exporting Stata dta files in version 118, ``StataWriter118``.  This format supports exporting strings containing Unicode characters (:issue:`23573`)
 - :meth:`Series.map` now accepts ``collections.abc.Mapping`` subclasses as a mapper (:issue:`29733`)
 - The ``pandas.datetime`` class is now deprecated. Import from ``datetime`` instead (:issue:`30296`)
+- :meth:`Timestamp.fromisocalendar` is now compatible with python 3.8 and above (:issue:`28115`)
 
 
 

pandas/_libs/tslibs/nattype.pyx

@@ -5,6 +5,9 @@ from cpython.object cimport (
 from cpython.datetime cimport (datetime,
                                PyDateTime_Check, PyDelta_Check,
                                PyDateTime_IMPORT)
+
+from cpython.version cimport PY_MINOR_VERSION
+
 PyDateTime_IMPORT
 
 import numpy as np
@@ -19,6 +22,7 @@ from pandas._libs.tslibs.util cimport (
     get_nat, is_integer_object, is_float_object, is_datetime64_object,
     is_timedelta64_object)
 
+
 # ----------------------------------------------------------------------
 # Constants
 nat_strings = {'NaT', 'nat', 'NAT', 'nan', 'NaN', 'NAN'}
@@ -427,6 +431,10 @@ class NaTType(_NaT):
     tzname = _make_error_func('tzname', datetime)
     utcoffset = _make_error_func('utcoffset', datetime)
 
+    # "fromisocalendar" was introduced in 3.8
+    if PY_MINOR_VERSION >= 8:
+        fromisocalendar = _make_error_func('fromisocalendar', datetime)
+
     # ----------------------------------------------------------------------
     # The remaining methods have docstrings copy/pasted from the analogous
     # Timestamp methods.

pandas/tests/scalar/test_nat.py

@@ -123,6 +123,13 @@ def test_round_nat(klass, method, freq):
         "dst",
         "fromordinal",
         "fromtimestamp",
+        pytest.param(
+            "fromisocalendar",
+            marks=pytest.mark.skipif(
+                not compat.PY38,
+                reason="'fromisocalendar' was added in stdlib datetime in python 3.8",
+            ),
+        ),
         "isocalendar",
         "strftime",
         "strptime",
@@ -297,6 +304,8 @@ def test_overlap_public_nat_methods(klass, expected):
     # "fromisoformat" was introduced in 3.7
     if klass is Timestamp and not compat.PY37:
         expected.remove("fromisoformat")
+
+    # "fromisocalendar" was introduced in 3.8
     if klass is Timestamp and not compat.PY38:
         expected.remove("fromisocalendar")
 

pandas/tests/scalar/timestamp/test_timestamp.py

@@ -14,6 +14,7 @@
 
 from pandas._libs.tslibs import conversion
 from pandas._libs.tslibs.timezones import dateutil_gettz as gettz, get_timezone
+import pandas.compat as compat
 from pandas.compat.numpy import np_datetime64_compat
 from pandas.errors import OutOfBoundsDatetime
 import pandas.util._test_decorators as td
@@ -700,6 +701,19 @@ class SubDatetime(datetime):
         expected = Timestamp(2000, 1, 1)
         assert result == expected
 
+    @pytest.mark.skipif(
+        not compat.PY38,
+        reason="datetime.fromisocalendar was added in Python version 3.8",
+    )
+    def test_constructor_fromisocalendar(self):
+        # GH 30395
+        expected_timestamp = Timestamp("2000-01-03 00:00:00")
+        expected_stdlib = datetime.fromisocalendar(2000, 1, 1)
+        result = Timestamp.fromisocalendar(2000, 1, 1)
+        assert result == expected_timestamp
+        assert result == expected_stdlib
+        assert isinstance(result, Timestamp)
+
 
 class TestTimestamp:
     def test_tz(self):