monkeypatch: add support for TypedDict

AUTHORS

@@ -8,6 +8,7 @@ Abdeali JK
 Abdelrahman Elbehery
 Abhijeet Kasurde
 Adam Johnson
+Adam Stewart
 Adam Uhlir
 Ahn Ki-Wook
 Akiomi Kamakura

changelog/10999.bugfix.rst

@@ -0,0 +1 @@
+Fixed bug where monkeypatch setitem/delitem type annotations didn't support typing.TypedDict.

src/_pytest/monkeypatch.py

@@ -7,7 +7,7 @@
 from typing import Any
 from typing import Generator
 from typing import List
-from typing import MutableMapping
+from typing import Mapping
 from typing import Optional
 from typing import overload
 from typing import Tuple
@@ -129,7 +129,7 @@ class MonkeyPatch:
 
     def __init__(self) -> None:
         self._setattr: List[Tuple[object, str, object]] = []
-        self._setitem: List[Tuple[MutableMapping[Any, Any], object, object]] = []
+        self._setitem: List[Tuple[Mapping[Any, Any], object, object]] = []
         self._cwd: Optional[str] = None
         self._savesyspath: Optional[List[str]] = None
 
@@ -290,12 +290,17 @@ def delattr(
             self._setattr.append((target, name, oldval))
             delattr(target, name)
 
-    def setitem(self, dic: MutableMapping[K, V], name: K, value: V) -> None:
+    def setitem(self, dic: Mapping[K, V], name: K, value: V) -> None:
         """Set dictionary entry ``name`` to value."""
         self._setitem.append((dic, name, dic.get(name, notset)))
         dic[name] = value
 
-    def delitem(self, dic: MutableMapping[K, V], name: K, raising: bool = True) -> None:
+    def delitem(
+        self,
+        dic: Mapping[K, V],
+        name: K,
+        raising: bool = True,
+    ) -> None:
         """Delete ``name`` from dict.
 
         Raises ``KeyError`` if it doesn't exist, unless ``raising`` is set to
@@ -336,7 +341,7 @@ def delenv(self, name: str, raising: bool = True) -> None:
         Raises ``KeyError`` if it does not exist, unless ``raising`` is set to
         False.
         """
-        environ: MutableMapping[str, str] = os.environ
+        environ: Mapping[str, str] = os.environ
         self.delitem(environ, name, raising=raising)
 
     def syspath_prepend(self, path) -> None:

testing/typing_checks.py

@@ -4,11 +4,13 @@
 none of the code triggers any mypy errors.
 """
 import contextlib
+import sys
 from typing import Optional
 
 from typing_extensions import assert_type
 
 import pytest
+from _pytest.monkeypatch import MonkeyPatch
 
 
 # Issue #7488.
@@ -29,6 +31,22 @@ def check_parametrize_ids_callable(func) -> None:
     pass
 
 
+# Issue #10999.
+@pytest.mark.skipif(
+    sys.version_info < (3, 8), reason="TypedDict introduced in Python 3.8"
+)
+def check_monkeypatch_typeddict(monkeypatch: MonkeyPatch) -> None:
+    from typing import TypedDict
+
+    class Foo(TypedDict):
+        x: int
+        y: float
+
+    a: Foo = {"x": 1, "y": 3.14}
+    monkeypatch.setitem("x", 2)
+    monkeypatch.delitem("y")
+
+
 def check_raises_is_a_context_manager(val: bool) -> None:
     with pytest.raises(RuntimeError) if val else contextlib.nullcontext() as excinfo:
         pass