fix: handle infinite relative tolerance for timedelta values

AUTHORS

@@ -288,6 +288,7 @@ lovetheguitar
 Lukas Bednar
 Luke Murphy
 Maciek Fijalkowski
+Madan Kumar
 Maggie Chung
 Maho
 Maik Figura

changelog/14754.bugfix.rst

@@ -0,0 +1 @@
+``pytest.approx()`` now rejects infinite relative tolerances for ``datetime.timedelta`` values with a clear ``ValueError`` instead of raising ``OverflowError``.

src/_pytest/approx.py

@@ -677,6 +677,8 @@ def __init__(
                 raise ValueError(f"relative tolerance can't be negative: {rel}")
             if math.isnan(rel):
                 raise ValueError("relative tolerance can't be NaN.")
+            if math.isinf(rel):
+                raise ValueError("relative tolerance can't be infinite.")
         # Compute the effective tolerance. abs_tolerance is a timedelta, rel * expected
         # gives a timedelta (timedelta * float works in Python).
         abs_tolerance = abs

testing/python/approx.py

@@ -1251,6 +1251,12 @@ def test_timedelta_rel_must_not_be_nan(self):
         with pytest.raises(ValueError, match="relative tolerance can't be NaN"):
             approx(timedelta(seconds=1), rel=float("nan"))
 
+    def test_timedelta_rel_must_not_be_infinite(self):
+        from datetime import timedelta
+
+        with pytest.raises(ValueError, match="relative tolerance can't be infinite"):
+            approx(timedelta(seconds=1), rel=inf)
+
     def test_timedelta_abs_must_be_non_negative(self):
         from datetime import timedelta