Fix arithmetic with standard timedelta operands

Author: Eric3-jp

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
@@ -356,6 +355,14 @@ def __neg__(self) -> Self:
     def _to_microseconds(self) -> int:
         return (self._days * (24 * 3600) + self._seconds) * 1000000 + self._microseconds
 
+    @staticmethod
+    def _timedelta_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
+
     def __mul__(self, other: int | float) -> Self:
         if isinstance(other, int):
             return self.__class__(
@@ -386,10 +393,7 @@ 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 // self._timedelta_microseconds(other)
 
         if isinstance(other, int):
             return self.__class__(
@@ -412,10 +416,7 @@ 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 / self._timedelta_microseconds(other)
 
         if isinstance(other, int):
             return self.__class__(
@@ -441,7 +442,7 @@ 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() % self._timedelta_microseconds(other)
 
             return self.__class__(0, 0, r)
 
@@ -451,7 +452,7 @@ 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]
+                self._timedelta_microseconds(other),
             )
 
             return q, self.__class__(0, 0, r)

tests/duration/test_arithmetic.py

@@ -1,10 +1,50 @@
 from __future__ import annotations
 
+import operator
+
+from datetime import timedelta
+from typing import TYPE_CHECKING
+
+import pytest
+
 import pendulum
 
 from tests.conftest import assert_duration
 
 
+if TYPE_CHECKING:
+    from collections.abc import Callable
+
+
+@pytest.mark.parametrize(
+    "operation", [operator.truediv, operator.floordiv, operator.mod, divmod]
+)
+@pytest.mark.parametrize(
+    "divisor", [timedelta(days=1), timedelta(seconds=-2), timedelta(microseconds=3)]
+)
+def test_arithmetic_with_standard_timedelta(
+    operation: Callable[[timedelta, timedelta], object], divisor: timedelta
+) -> None:
+    expected = timedelta(days=2, seconds=35, microseconds=522222)
+    duration = pendulum.duration(days=2, seconds=35, microseconds=522222)
+    assert operation(duration, divisor) == operation(expected, divisor)
+
+
+@pytest.mark.parametrize(
+    "operation", [operator.truediv, operator.floordiv, operator.mod, divmod]
+)
+def test_arithmetic_with_zero_timedelta(
+    operation: Callable[[timedelta, timedelta], object],
+) -> None:
+    with pytest.raises(ZeroDivisionError):
+        operation(pendulum.duration(seconds=1), timedelta())
+
+
+def test_timedelta_divisor_keeps_large_microsecond_precision() -> None:
+    divisor = timedelta(days=200000, microseconds=1)
+    assert pendulum.duration(days=200000) // divisor == 0
+
+
 def test_multiply():
     it = pendulum.duration(days=6, seconds=34, microseconds=522222)
     mul = it * 2

tests/interval/test_arithmetic.py

@@ -1,10 +1,23 @@
 from __future__ import annotations
 
+from datetime import timedelta
+
 import pendulum
 
 from tests.conftest import assert_duration
 
 
+def test_arithmetic_with_standard_timedelta():
+    start = pendulum.datetime(2019, 1, 1)
+    interval = pendulum.interval(start, start.add(hours=25))
+    day = timedelta(days=1)
+
+    assert interval / day == 25 / 24
+    assert interval // day == 1
+    assert interval % day == timedelta(hours=1)
+    assert divmod(interval, day) == (1, timedelta(hours=1))
+
+
 def test_multiply():
     dt1 = pendulum.DateTime(2016, 8, 7, 12, 34, 56)
     dt2 = dt1.add(days=6, seconds=34)