Support native timedelta operands in duration arithmetic

src/pendulum/duration.py

@@ -2,7 +2,6 @@
 
 from datetime import timedelta
 from typing import TYPE_CHECKING
-from typing import cast
 from typing import overload
 
 import pendulum
@@ -43,6 +42,15 @@ def _divide_and_round(a: float, b: float) -> int:
     return q
 
 
+def _timedelta_to_microseconds(delta: timedelta) -> int:
+    if isinstance(delta, Duration):
+        return delta._to_microseconds()
+
+    return (
+        delta.days * SECONDS_PER_DAY + delta.seconds
+    ) * US_PER_SECOND + delta.microseconds
+
+
 class Duration(timedelta):
     """
     Replacement for the standard timedelta class.
@@ -386,10 +394,7 @@ def __floordiv__(self, other: int | timedelta) -> int | Duration:
 
         usec = self._to_microseconds()
         if isinstance(other, timedelta):
-            return cast(
-                "int",
-                usec // other._to_microseconds(),  # type: ignore[attr-defined]
-            )
+            return usec // _timedelta_to_microseconds(other)
 
         if isinstance(other, int):
             return self.__class__(
@@ -412,10 +417,7 @@ def __truediv__(self, other: int | float | timedelta) -> Self | float:
 
         usec = self._to_microseconds()
         if isinstance(other, timedelta):
-            return cast(
-                "float",
-                usec / other._to_microseconds(),  # type: ignore[attr-defined]
-            )
+            return usec / _timedelta_to_microseconds(other)
 
         if isinstance(other, int):
             return self.__class__(
@@ -441,7 +443,7 @@ def __truediv__(self, other: int | float | timedelta) -> Self | float:
 
     def __mod__(self, other: timedelta) -> Self:
         if isinstance(other, timedelta):
-            r = self._to_microseconds() % other._to_microseconds()  # type: ignore[attr-defined]
+            r = self._to_microseconds() % _timedelta_to_microseconds(other)
 
             return self.__class__(0, 0, r)
 
@@ -451,7 +453,7 @@ def __divmod__(self, other: timedelta) -> tuple[int, Duration]:
         if isinstance(other, timedelta):
             q, r = divmod(
                 self._to_microseconds(),
-                other._to_microseconds(),  # type: ignore[attr-defined]
+                _timedelta_to_microseconds(other),
             )
 
             return q, self.__class__(0, 0, r)

tests/duration/test_arithmetic.py

@@ -1,5 +1,11 @@
 from __future__ import annotations
 
+import operator
+
+from datetime import timedelta
+
+import pytest
+
 import pendulum
 
 from tests.conftest import assert_duration
@@ -83,3 +89,28 @@ def test_floor_divide():
 
     assert isinstance(mul, pendulum.Duration)
     assert_duration(mul, 0, 1, 0, 0, 16, 0, 11, 840740)
+
+
+@pytest.mark.parametrize(
+    "operation", [operator.truediv, operator.floordiv, operator.mod, divmod]
+)
+@pytest.mark.parametrize(
+    "divisor",
+    [
+        timedelta(seconds=2, microseconds=1),
+        timedelta(seconds=-2, microseconds=1),
+        timedelta(days=500_000, microseconds=1),
+    ],
+)
+def test_arithmetic_with_native_timedelta(operation, divisor):
+    native = timedelta(days=1, seconds=1, microseconds=3)
+    duration = pendulum.duration(days=1, seconds=1, microseconds=3)
+    assert operation(duration, divisor) == operation(native, divisor)
+
+
+@pytest.mark.parametrize(
+    "operation", [operator.truediv, operator.floordiv, operator.mod, divmod]
+)
+def test_arithmetic_with_zero_native_timedelta(operation):
+    with pytest.raises(ZeroDivisionError):
+        operation(pendulum.duration(seconds=1), timedelta())