fix: resolve flaky tenant input validation in Python 3.12

Use  instead of  for runtime
issubclass/isinstance checks in the input validator. The typing module's
Sequence can produce flaky isinstance() results in Python 3.12+ due to
internal changes in the typing module, causing valid Sequence inputs
(e.g., a list of Tenant objects) to be incorrectly rejected.

Also adds targeted test coverage for the Sequence[Union[...]] validation
pattern that reproduces the reported failure scenario.

Author: PrinceRaymondPaul911

test/collection/test_validator.py

@@ -1,4 +1,4 @@
-from typing import Any, List
+from typing import Any, List, Sequence, Union
 
 import numpy as np
 import pandas as pd
@@ -28,6 +28,14 @@
             False,
         ),
         (pl.Series([1, 1]), [_ExtraTypes.PANDAS, _ExtraTypes.NUMPY, List], True),
+        # Tests for Sequence[Union[...]] pattern, which was flaky in Python 3.12
+        (["a", 1], [Sequence[Union[str, int]]], False),
+        ([1, "a"], [Sequence[Union[str, int]]], False),
+        ([1, 2], [Sequence[Union[str, int]]], False),
+        (["a", "b"], [Sequence[Union[str, int]]], False),
+        (["a", 1], [str, Sequence[Union[str, int]]], False),  # matches Sequence[Union[str, int]]
+        # Non-sequence values are not valid Sequence types: int is not iterable
+        (42, [Sequence[Union[str, int]]], True),
     ],
 )
 def test_validator(inputs: Any, expected: List[Any], error: bool) -> None:

weaviate/validator.py

@@ -1,3 +1,4 @@
+from collections.abc import Sequence as ABCSequence
 from dataclasses import dataclass
 from typing import Any, List, Sequence, Union, get_args, get_origin
 
@@ -48,9 +49,9 @@ def _is_valid(expected: Any, value: Any) -> bool:
         args = get_args(expected)
         return any(isinstance(value, arg) for arg in args)
     if expected_origin is not None and (
-        issubclass(expected_origin, Sequence) or expected_origin is list
+        issubclass(expected_origin, ABCSequence) or expected_origin is list
     ):
-        if not isinstance(value, Sequence) and not isinstance(value, list):
+        if not isinstance(value, (ABCSequence, list)):
             return False
         args = get_args(expected)
         if len(args) == 1: