From 88354a903af6fc69b599fafe57506d1f03c37b7c Mon Sep 17 00:00:00 2001
From: Alex Waygood <Alex.Waygood@Gmail.com>
Date: Mon, 3 Jan 2022 18:39:32 +0000
Subject: [PATCH 1/3] Make mypy test suite pass mypy on Windows

---
 mypy/test/data.py | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/mypy/test/data.py b/mypy/test/data.py
index e886b11ffa8e..721d9172680b 100644
--- a/mypy/test/data.py
+++ b/mypy/test/data.py
@@ -10,10 +10,26 @@
 import sys
 
 import pytest
-from typing import List, Tuple, Set, Optional, Iterator, Any, Dict, NamedTuple, Union
+from typing import (
+    List,
+    Protocol,
+    Tuple,
+    TYPE_CHECKING,
+    Set,
+    Optional,
+    Iterator,
+    Any,
+    Dict,
+    NamedTuple,
+    Union,
+    overload
+)
 
 from mypy.test.config import test_data_prefix, test_temp_dir, PREFIX
 
+if TYPE_CHECKING:
+    from _typeshed import BytesPath, StrPath
+
 root_dir = os.path.normpath(PREFIX)
 
 # File modify/create operation: copy module contents from source_path.
@@ -28,6 +44,18 @@
 FileOperation = Union[UpdateFile, DeleteFile]
 
 
+class JoinFunction(Protocol):
+    """A callback protocol with which both `ntpath.join()` and `posixpath.join()` are compliant.
+
+    The two functions have different parameter names,
+    meaning this file doesn't type-check on Windows without this protocol.
+    """
+    @overload
+    def __call__(self, __path: 'StrPath', *paths: 'StrPath') -> str: ...
+    @overload
+    def __call__(self, __path: 'BytesPath', *paths: 'BytesPath') -> bytes: ...
+
+
 def parse_test_case(case: 'DataDrivenTestCase') -> None:
     """Parse and prepare a single case from suite with test case descriptions.
 
@@ -35,6 +63,7 @@ def parse_test_case(case: 'DataDrivenTestCase') -> None:
     """
     test_items = parse_test_data(case.data, case.name)
     base_path = case.suite.base_path
+    join: JoinFunction
     if case.suite.native_sep:
         join = os.path.join
     else:

From 44f9eb7f4183804aab6734972e5941aef89c7405 Mon Sep 17 00:00:00 2001
From: Alex Waygood <Alex.Waygood@Gmail.com>
Date: Mon, 3 Jan 2022 18:58:23 +0000
Subject: [PATCH 2/3] Update data.py

---
 mypy/test/data.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mypy/test/data.py b/mypy/test/data.py
index 721d9172680b..be5b0cea3bf4 100644
--- a/mypy/test/data.py
+++ b/mypy/test/data.py
@@ -12,7 +12,6 @@
 import pytest
 from typing import (
     List,
-    Protocol,
     Tuple,
     TYPE_CHECKING,
     Set,
@@ -24,6 +23,7 @@
     Union,
     overload
 )
+from typing_extensions import Protocol
 
 from mypy.test.config import test_data_prefix, test_temp_dir, PREFIX
 

From 4be969d8ade43c8f8391e21cbb4adedde171e275 Mon Sep 17 00:00:00 2001
From: Alex Waygood <Alex.Waygood@Gmail.com>
Date: Tue, 4 Jan 2022 08:31:44 +0000
Subject: [PATCH 3/3] Update data.py

---
 mypy/test/data.py | 33 +++------------------------------
 1 file changed, 3 insertions(+), 30 deletions(-)

diff --git a/mypy/test/data.py b/mypy/test/data.py
index be5b0cea3bf4..c4eefad6592c 100644
--- a/mypy/test/data.py
+++ b/mypy/test/data.py
@@ -10,26 +10,10 @@
 import sys
 
 import pytest
-from typing import (
-    List,
-    Tuple,
-    TYPE_CHECKING,
-    Set,
-    Optional,
-    Iterator,
-    Any,
-    Dict,
-    NamedTuple,
-    Union,
-    overload
-)
-from typing_extensions import Protocol
+from typing import Callable, List, Tuple, Set, Optional, Iterator, Any, Dict, NamedTuple, Union
 
 from mypy.test.config import test_data_prefix, test_temp_dir, PREFIX
 
-if TYPE_CHECKING:
-    from _typeshed import BytesPath, StrPath
-
 root_dir = os.path.normpath(PREFIX)
 
 # File modify/create operation: copy module contents from source_path.
@@ -44,18 +28,6 @@
 FileOperation = Union[UpdateFile, DeleteFile]
 
 
-class JoinFunction(Protocol):
-    """A callback protocol with which both `ntpath.join()` and `posixpath.join()` are compliant.
-
-    The two functions have different parameter names,
-    meaning this file doesn't type-check on Windows without this protocol.
-    """
-    @overload
-    def __call__(self, __path: 'StrPath', *paths: 'StrPath') -> str: ...
-    @overload
-    def __call__(self, __path: 'BytesPath', *paths: 'BytesPath') -> bytes: ...
-
-
 def parse_test_case(case: 'DataDrivenTestCase') -> None:
     """Parse and prepare a single case from suite with test case descriptions.
 
@@ -63,7 +35,8 @@ def parse_test_case(case: 'DataDrivenTestCase') -> None:
     """
     test_items = parse_test_data(case.data, case.name)
     base_path = case.suite.base_path
-    join: JoinFunction
+    # this file doesn't type-check on Windows without this line, see #11895
+    join: Callable[[str, str], str]
     if case.suite.native_sep:
         join = os.path.join
     else: