Fix intcomma overflow for large Python integers (#392)

Author: Yananix

src/humanize/number.py

@@ -160,7 +160,7 @@ def intcomma(value: NumberOrString, ndigits: int | None = None) -> str:
                 value = float(value)
             else:
                 value = int(value)
-        else:
+        elif not isinstance(value, int):
             if not math.isfinite(float(value)):
                 return _format_not_finite(float(value))
             float(value)

tests/test_number.py

@@ -83,6 +83,13 @@ def test_intcomma(
     assert humanize.intcomma(*test_args) == expected
 
 
+@pytest.mark.parametrize("sign", [1, -1])
+def test_intcomma_large_integer(sign: int) -> None:
+    value = sign * (10**400 + 123)
+    expected = ("-" if sign < 0 else "") + "10" + ",000" * 132 + ",123"
+    assert humanize.intcomma(value) == expected
+
+
 def test_intword_powers() -> None:
     # make sure that powers & human_powers have the same number of items
     assert len(number.powers) == len(number.human_powers)