4 files changed, 54 insertions, 8 deletions

diff --git a/lib/sqlalchemy/testing/config.py b/lib/sqlalchemy/testing/config.py
index 268a56421..c1ca670da 100644
--- a/lib/sqlalchemy/testing/config.py
+++ b/lib/sqlalchemy/testing/config.py
@@ -6,6 +6,11 @@
 # the MIT License: https://www.opensource.org/licenses/mit-license.php
 
 import collections
+import typing
+from typing import Any
+from typing import Iterable
+from typing import Tuple
+from typing import Union
 
 from .. import util
 
@@ -20,10 +25,15 @@ any_async = False
 _current = None
 ident = "main"
 
-_fixture_functions = None  # installed by plugin_base
+if typing.TYPE_CHECKING:
+    from .plugin.plugin_base import FixtureFunctions
 
+    _fixture_functions: FixtureFunctions
+else:
+    _fixture_functions = None  # installed by plugin_base
 
-def combinations(*comb, **kw):
+
+def combinations(*comb: Union[Any, Tuple[Any, ...]], **kw: str):
     r"""Deliver multiple versions of a test based on positional combinations.
 
     This is a facade over pytest.mark.parametrize.
@@ -89,25 +99,32 @@ def combinations(*comb, **kw):
     return _fixture_functions.combinations(*comb, **kw)
 
 
-def combinations_list(arg_iterable, **kw):
+def combinations_list(
+    arg_iterable: Iterable[
+        Tuple[
+            Any,
+        ]
+    ],
+    **kw,
+):
     "As combination, but takes a single iterable"
     return combinations(*arg_iterable, **kw)
 
 
-def fixture(*arg, **kw):
+def fixture(*arg: Any, **kw: Any) -> Any:
     return _fixture_functions.fixture(*arg, **kw)
 
 
-def get_current_test_name():
+def get_current_test_name() -> str:
     return _fixture_functions.get_current_test_name()
 
 
-def mark_base_test_class():
+def mark_base_test_class() -> Any:
     return _fixture_functions.mark_base_test_class()
 
 
 class _AddToMarker:
-    def __getattr__(self, attr):
+    def __getattr__(self, attr: str) -> Any:
         return getattr(_fixture_functions.add_to_marker, attr)
 
 
diff --git a/lib/sqlalchemy/testing/fixtures.py b/lib/sqlalchemy/testing/fixtures.py
index ecc20f163..7228e5afe 100644
--- a/lib/sqlalchemy/testing/fixtures.py
+++ b/lib/sqlalchemy/testing/fixtures.py
@@ -20,6 +20,7 @@ from .util import drop_all_tables_from_metadata
 from .. import event
 from .. import util
 from ..orm import declarative_base
+from ..orm import DeclarativeBase
 from ..orm import registry
 from ..schema import sort_tables_and_constraints
 
@@ -82,6 +83,21 @@ class TestBase:
         yield reg
         reg.dispose()
 
+    @config.fixture
+    def decl_base(self, metadata):
+        _md = metadata
+
+        class Base(DeclarativeBase):
+            metadata = _md
+            type_annotation_map = {
+                str: sa.String().with_variant(
+                    sa.String(50), "mysql", "mariadb"
+                )
+            }
+
+        yield Base
+        Base.registry.dispose()
+
     @config.fixture()
     def future_connection(self, future_engine, connection):
         # integrate the future_engine and connection fixtures so
diff --git a/lib/sqlalchemy/testing/plugin/plugin_base.py b/lib/sqlalchemy/testing/plugin/plugin_base.py
index 0b4451b3c..52e42bb97 100644
--- a/lib/sqlalchemy/testing/plugin/plugin_base.py
+++ b/lib/sqlalchemy/testing/plugin/plugin_base.py
@@ -19,6 +19,7 @@ import logging
 import os
 import re
 import sys
+from typing import Any
 
 from sqlalchemy.testing import asyncio
 
@@ -738,7 +739,7 @@ class FixtureFunctions(abc.ABC):
         raise NotImplementedError()
 
     @abc.abstractmethod
-    def mark_base_test_class(self):
+    def mark_base_test_class(self) -> Any:
         raise NotImplementedError()
 
     @abc.abstractproperty
diff --git a/lib/sqlalchemy/testing/requirements.py b/lib/sqlalchemy/testing/requirements.py
index 410ab26ed..41e5d6772 100644
--- a/lib/sqlalchemy/testing/requirements.py
+++ b/lib/sqlalchemy/testing/requirements.py
@@ -1326,6 +1326,18 @@ class SuiteRequirements(Requirements):
         return exclusions.only_if(check)
 
     @property
+    def no_sqlalchemy2_stubs(self):
+        def check(config):
+            try:
+                __import__("sqlalchemy-stubs.ext.mypy")
+            except ImportError:
+                return False
+            else:
+                return True
+
+        return exclusions.skip_if(check)
+
+    @property
     def python38(self):
         return exclusions.only_if(
             lambda: util.py38, "Python 3.8 or above required"