diff --git a/test/test_str_enum.py b/test/test_str_enum.py
new file mode 100644
index 000000000..dbb3d8a6b
--- /dev/null
+++ b/test/test_str_enum.py
@@ -0,0 +1,31 @@
+from weaviate.str_enum import BaseEnum
+
+
+class _Color(BaseEnum):
+    RED = "red"
+    GREEN = "green"
+
+
+def test_member_name_string_is_contained():
+    # `in` matches by member *name*, so the uppercase name is found.
+    assert "RED" in _Color
+    assert "GREEN" in _Color
+
+
+def test_unknown_string_is_not_contained():
+    assert "PURPLE" not in _Color
+
+
+def test_member_value_string_is_not_a_membership_match():
+    # The lowercase *value* is not a member name, so it is not contained.
+    assert "red" not in _Color
+
+
+def test_enum_member_is_contained():
+    assert _Color.RED in _Color
+
+
+def test_non_string_non_member_is_not_contained():
+    # A non-string that lacks a ``.name`` falls back to the string check
+    # and is therefore not contained.
+    assert 12345 not in _Color