Use get_typing_hints instead of __annotations__ to resolve types in P…

…ython 3.10 (#297)

Summary:
**What:**

Fixes #296

**Why:**

Due to PEP 563 becoming default in Python 3.10 the `__annotations__` value doesn't store types and it stores string values. Using `typing.get_type_hints` ensures the types are evaluated and returned like behavior before Python 3.10 .

**How:**

**Risks:**

**Checklist**:

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- [ ] Added tests, if you've added code that should be tested
- [ ] Updated the documentation, if you've changed APIs
- [ ] Ensured the test suite passes
- [ ] Made sure your code lints
- [ ] Completed the Contributor License Agreement ("CLA")

Pull Request resolved: #297

Reviewed By: lsiudut

Differential Revision: D27645783

Pulled By: deathowl

fbshipit-source-id: eb1d41abcccad9e5d6cc92554472e0d083bebf4f

testslide/strict_mock.py

@@ -7,7 +7,17 @@
 import inspect
 import os.path
 from types import FrameType
-from typing import TYPE_CHECKING, Any, Callable, Dict, List, Optional, Type, Union
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    Callable,
+    Dict,
+    List,
+    Optional,
+    Type,
+    Union,
+    get_type_hints,
+)
 
 import testslide.lib
 import testslide.mock_callable
@@ -623,8 +633,12 @@ def __validate_attribute_type(self, name: str, value: Any) -> None:
         ):
             return
 
-        if hasattr(self._template, "__annotations__"):
-            annotations = self._template.__annotations__
+        if self._template is not None:
+            try:
+                annotations = get_type_hints(self._template)
+            except Exception:
+                # Some modules can throw KeyError : https://bugs.python.org/issue41515
+                annotations = {}
             if name in annotations:
                 testslide.lib._validate_argument_type(annotations[name], name, value)