fix: validate the amount in Interval.range (zero/negative hang or run away)

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Change Log
 
+## Unreleased
+
+### Fixed
+- `Interval.range()` now raises `ValueError` for a non-positive `amount` instead of silently producing an infinite (amount <= 0... zero repeats the start forever, negative runs away from the end) or unbounded generator [#1080](https://github.com/python-pendulum/pendulum/issues/1080)
+
 ## [3.3.0] - 2026-10-12
 
 ### Added

src/pendulum/interval.py

@@ -288,6 +288,10 @@ def in_words(self, locale: str | None = None, separator: str = " ") -> str:
         return separator.join(parts)
 
     def range(self, unit: str, amount: int = 1) -> Iterator[_T]:
+        if amount <= 0:
+            msg = f"amount must be a positive integer, got {amount!r}"
+            raise ValueError(msg)
+
         method = "add"
         op = operator.le
         if not self._absolute and self.invert:

tests/interval/test_range.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+import pytest
+
 import pendulum
 
 from pendulum.interval import Interval
@@ -117,3 +119,15 @@ def test_range_amount():
     assert_datetime(r[1], 2016, 10, 16, 1, 0, 0)
     assert_datetime(r[2], 2016, 10, 18, 0, 0, 0)
     assert_datetime(r[3], 2016, 10, 20, 0, 0, 0)
+
+
+def test_range_zero_amount_raises():
+    p = Interval(pendulum.datetime(2016, 1, 1), pendulum.datetime(2016, 2, 1))
+    with pytest.raises(ValueError, match="positive integer"):
+        list(p.range("days", 0))
+
+
+def test_range_negative_amount_raises():
+    p = Interval(pendulum.datetime(2016, 1, 1), pendulum.datetime(2016, 2, 1))
+    with pytest.raises(ValueError, match="positive integer"):
+        list(p.range("days", -1))