@@ -23,6 +23,13 @@ def test_hex_to_rgb_shorthand_3_digit():
     assert hex_to_rgb("#00f") == (0, 0, 255)
 
 
+@pytest.mark.parametrize("value", ["#abcd", "eb4d", "#12345678", "b24fa3d1"])
+def test_hex_to_rgb_warns_on_4_and_8_digits(value):
+    warning_must_contain = "4-char" if len(value.lstrip("#")) == 4 else "8-char"
+    with pytest.warns(UserWarning, match=warning_must_contain):
+        hex_to_rgb(value)
+
+
 @pytest.mark.parametrize("value", ["#12345", "#1", "#1234567", "", "#"])
 def test_hex_to_rgb_rejects_other_lengths(value):
     # The section width was len // 3, so "#12345" returned a 5-tuple rather