fix precisedelta dropping sign of negative timedeltas (fixes #379)

src/humanize/time.py

@@ -5,6 +5,8 @@
 
 from __future__ import annotations
 
+import datetime
+
 __lazy_modules__ = {"humanize.i18n", "humanize.number"}
 
 from enum import Enum
@@ -546,6 +548,13 @@ def precisedelta(
 
     ```
     """
+    if isinstance(value, datetime.timedelta):
+        negative = value < datetime.timedelta(0)
+    elif isinstance(value, (int, float)):
+        negative = value < 0
+    else:
+        negative = False
+
     date, delta = _date_and_delta(value, precise=True)
     if date is None:
         return str(value)
@@ -673,12 +682,13 @@ def precisedelta(
             break
 
     if len(texts) == 1:
-        return texts[0]
-
-    head = ", ".join(texts[:-1])
-    tail = texts[-1]
+        result = texts[0]
+    else:
+        head = ", ".join(texts[:-1])
+        tail = texts[-1]
+        result = _("%s and %s") % (head, tail)
 
-    return _("%s and %s") % (head, tail)
+    return f"-{result}" if negative else result
 
 
 def _rounding_by_fmt(format: str, value: float) -> float | int:

tests/test_time.py

@@ -837,6 +837,23 @@ def test_precisedelta_suppress_units(
 def test_precisedelta_bogus_call() -> None:
     assert humanize.precisedelta(None) == "None"
 
+
+def test_precisedelta_negative() -> None:
+    # regression: negative timedeltas must keep their sign
+    # https://github.com/python-humanize/humanize/issues/379
+    assert (
+        humanize.precisedelta(dt.timedelta(seconds=-3661))
+        == "-1 hour, 1 minute and 1 second"
+    )
+    assert (
+        humanize.precisedelta(dt.timedelta(seconds=3661))
+        == "1 hour, 1 minute and 1 second"
+    )
+    assert (
+        humanize.precisedelta(dt.timedelta(seconds=-3661), minimum_unit="minutes")
+        == "-1 hour and 1.02 minutes"
+    )
+
     with pytest.raises(
         ValueError,
         match="Minimum unit is suppressed and no suitable replacement was found",