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ENH: Support for Orthodox Easter (pandas-dev#61666)
* Support for Orthodox Easter * Fix lint issues * Fix test * Fix lint * Fix lint issues * Fix lint * Fix lint * Fix lint * Fix lint * Fix * Updated whats new doc * Add validation * Fix review feedback * Fix lint
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‎doc/source/whatsnew/v3.0.0.rst‎

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@@ -64,6 +64,7 @@ Other enhancements
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- :meth:`Series.nlargest` uses a 'stable' sort internally and will preserve original ordering.
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- :class:`ArrowDtype` now supports ``pyarrow.JsonType`` (:issue:`60958`)
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- :class:`DataFrameGroupBy` and :class:`SeriesGroupBy` methods ``sum``, ``mean``, ``median``, ``prod``, ``min``, ``max``, ``std``, ``var`` and ``sem`` now accept ``skipna`` parameter (:issue:`15675`)
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- :class:`Easter` has gained a new constructor argument ``method`` which specifies the method used to calculate Easter — for example, Orthodox Easter (:issue:`61665`)
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- :class:`Holiday` has gained the constructor argument and field ``exclude_dates`` to exclude specific datetimes from a custom holiday calendar (:issue:`54382`)
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- :class:`Rolling` and :class:`Expanding` now support ``nunique`` (:issue:`26958`)
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- :class:`Rolling` and :class:`Expanding` now support aggregations ``first`` and ``last`` (:issue:`33155`)

‎pandas/_libs/tslibs/offsets.pyi‎

Lines changed: 7 additions & 1 deletion
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@@ -230,7 +230,13 @@ class FY5253Quarter(FY5253Mixin):
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variation: Literal["nearest", "last"] = ...,
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) -> None: ...
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233-
class Easter(SingleConstructorOffset): ...
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class Easter(SingleConstructorOffset):
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def __init__(
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self,
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n: int = ...,
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normalize: bool = ...,
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method: int = ...,
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) -> None: ...
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class _CustomBusinessMonth(BusinessMixin):
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def __init__(

‎pandas/_libs/tslibs/offsets.pyx‎

Lines changed: 26 additions & 3 deletions
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@@ -4520,6 +4520,12 @@ cdef class Easter(SingleConstructorOffset):
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The number of years represented.
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normalize : bool, default False
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Normalize start/end dates to midnight before generating date range.
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method : int, default 3
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The method used to calculate the date of Easter. Valid options are:
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- 1 (EASTER_JULIAN): Original calculation in Julian calendar
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- 2 (EASTER_ORTHODOX): Original method, date converted to Gregorian calendar
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- 3 (EASTER_WESTERN): Revised method, in Gregorian calendar
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These constants are defined in the `dateutil.easter` module.
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See Also
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--------
@@ -4532,15 +4538,32 @@ cdef class Easter(SingleConstructorOffset):
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Timestamp('2022-04-17 00:00:00')
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"""
45344540

4541+
_attributes = tuple(["n", "normalize", "method"])
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cdef readonly:
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int method
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from dateutil.easter import EASTER_WESTERN
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def __init__(self, n=1, normalize=False, method=EASTER_WESTERN):
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BaseOffset.__init__(self, n, normalize)
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self.method = method
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if method < 1 or method > 3:
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raise ValueError(f"Method must be 1<=method<=3, got {method}")
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cpdef __setstate__(self, state):
4557+
from dateutil.easter import EASTER_WESTERN
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self.n = state.pop("n")
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self.normalize = state.pop("normalize")
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self.method = state.pop("method", EASTER_WESTERN)
45384561

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@apply_wraps
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def _apply(self, other: datetime) -> datetime:
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from dateutil.easter import easter
45424565

4543-
current_easter = easter(other.year)
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current_easter = easter(other.year, method=self.method)
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current_easter = datetime(
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current_easter.year, current_easter.month, current_easter.day
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)
@@ -4555,7 +4578,7 @@ cdef class Easter(SingleConstructorOffset):
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# NOTE: easter returns a datetime.date so we have to convert to type of
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# other
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new = easter(other.year + n)
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new = easter(other.year + n, method=self.method)
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new = datetime(
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new.year,
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new.month,
@@ -4573,7 +4596,7 @@ cdef class Easter(SingleConstructorOffset):
45734596

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from dateutil.easter import easter
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return date(dt.year, dt.month, dt.day) == easter(dt.year)
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return date(dt.year, dt.month, dt.day) == easter(dt.year, method=self.method)
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45784601

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# ----------------------------------------------------------------------

‎pandas/tests/tseries/offsets/test_easter.py‎

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Original file line numberDiff line numberDiff line change
@@ -7,6 +7,10 @@
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from datetime import datetime
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from dateutil.easter import (
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EASTER_ORTHODOX,
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EASTER_WESTERN,
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)
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import pytest
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from pandas.tests.tseries.offsets.common import assert_offset_equal
@@ -32,3 +36,115 @@ class TestEaster:
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)
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def test_offset(self, offset, date, expected):
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assert_offset_equal(offset, date, expected)
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@pytest.mark.parametrize(
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"offset,date,expected",
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[
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(Easter(method=EASTER_WESTERN), datetime(2010, 1, 1), datetime(2010, 4, 4)),
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(
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Easter(method=EASTER_WESTERN),
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datetime(2010, 4, 5),
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datetime(2011, 4, 24),
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),
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(
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Easter(2, method=EASTER_WESTERN),
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datetime(2010, 1, 1),
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datetime(2011, 4, 24),
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),
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(
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Easter(method=EASTER_WESTERN),
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datetime(2010, 4, 4),
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datetime(2011, 4, 24),
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),
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(
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Easter(2, method=EASTER_WESTERN),
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datetime(2010, 4, 4),
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datetime(2012, 4, 8),
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),
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(
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-Easter(method=EASTER_WESTERN),
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datetime(2011, 1, 1),
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datetime(2010, 4, 4),
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),
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(
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-Easter(method=EASTER_WESTERN),
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datetime(2010, 4, 5),
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datetime(2010, 4, 4),
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),
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(
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-Easter(2, method=EASTER_WESTERN),
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datetime(2011, 1, 1),
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datetime(2009, 4, 12),
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),
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(
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-Easter(method=EASTER_WESTERN),
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datetime(2010, 4, 4),
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datetime(2009, 4, 12),
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),
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(
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-Easter(2, method=EASTER_WESTERN),
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datetime(2010, 4, 4),
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datetime(2008, 3, 23),
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),
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],
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)
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def test_western_easter_offset(self, offset, date, expected):
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assert_offset_equal(offset, date, expected)
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94+
@pytest.mark.parametrize(
95+
"offset,date,expected",
96+
[
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(
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Easter(method=EASTER_ORTHODOX),
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datetime(2010, 1, 1),
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datetime(2010, 4, 4),
101+
),
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(
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Easter(method=EASTER_ORTHODOX),
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datetime(2010, 4, 5),
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datetime(2011, 4, 24),
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),
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(
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Easter(2, method=EASTER_ORTHODOX),
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datetime(2010, 1, 1),
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datetime(2011, 4, 24),
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),
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(
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Easter(method=EASTER_ORTHODOX),
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datetime(2010, 4, 4),
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datetime(2011, 4, 24),
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),
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(
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Easter(2, method=EASTER_ORTHODOX),
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datetime(2010, 4, 4),
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datetime(2012, 4, 15),
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),
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(
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-Easter(method=EASTER_ORTHODOX),
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datetime(2011, 1, 1),
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datetime(2010, 4, 4),
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),
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(
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-Easter(method=EASTER_ORTHODOX),
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datetime(2010, 4, 5),
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datetime(2010, 4, 4),
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),
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(
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-Easter(2, method=EASTER_ORTHODOX),
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datetime(2011, 1, 1),
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datetime(2009, 4, 19),
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),
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(
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-Easter(method=EASTER_ORTHODOX),
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datetime(2010, 4, 4),
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datetime(2009, 4, 19),
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),
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(
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-Easter(2, method=EASTER_ORTHODOX),
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datetime(2010, 4, 4),
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datetime(2008, 4, 27),
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),
147+
],
148+
)
149+
def test_orthodox_easter_offset(self, offset, date, expected):
150+
assert_offset_equal(offset, date, expected)

‎pandas/tests/tseries/offsets/test_offsets.py‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -239,7 +239,7 @@ def test_offset_freqstr(self, offset_types):
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offset = _create_offset(offset_types)
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241241
freqstr = offset.freqstr
242-
if freqstr not in ("<Easter>", "<DateOffset: days=1>", "LWOM-SAT"):
242+
if freqstr not in ("<Easter: method=3>", "<DateOffset: days=1>", "LWOM-SAT"):
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code = _get_offset(freqstr)
244244
assert offset.rule_code == code
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