Raise `ValueError` on negative `max_units`.

2 files changed, 9 insertions, 3 deletions

diff --git a/bot/utils/time.py b/bot/utils/time.py
index 183eff986..2aea2c099 100644
--- a/bot/utils/time.py
+++ b/bot/utils/time.py
@@ -35,6 +35,9 @@ def humanize_delta(delta: relativedelta, precision: str = "seconds", max_units:
     precision specifies the smallest unit of time to include (e.g. "seconds", "minutes").
     max_units specifies the maximum number of units of time to include (e.g. 1 may include days but not hours).
     """
+    if max_units <= 0:
+        raise ValueError("max_units must be positive")
+
     units = (
         ("years", delta.years),
         ("months", delta.months),
diff --git a/tests/utils/test_time.py b/tests/utils/test_time.py
index 61dd55c4a..4baa6395c 100644
--- a/tests/utils/test_time.py
+++ b/tests/utils/test_time.py
@@ -24,9 +24,6 @@ from tests.helpers import AsyncMock
         # Very high maximum units, but it only ever iterates over
         # each value the relativedelta might have.
         (relativedelta(days=2, hours=2), 'hours', 20, '2 days and 2 hours'),
-
-        # Negative maximum units.
-        (relativedelta(days=2, hours=2), 'hours', -1, 'less than a hour'),
     )
 )
 def test_humanize_delta(
@@ -38,6 +35,12 @@ def test_humanize_delta(
     assert time.humanize_delta(delta, precision, max_units) == expected
 
 
[email protected]('max_units', (-1, 0))
+def test_humanize_delta_raises_for_invalid_max_units(max_units: int):
+    with pytest.raises(ValueError, match='max_units must be positive'):
+        time.humanize_delta(relativedelta(days=2, hours=2), 'hours', max_units)
+
+
 @pytest.mark.parametrize(
     ('stamp', 'expected'),
     (