Implement closed support in astdiff

Author: alicederyn

mypy/server/astdiff.py

@@ -497,7 +497,7 @@ def visit_typeddict_type(self, typ: TypedDictType) -> SnapshotItem:
         items = tuple((key, snapshot_type(item_type)) for key, item_type in typ.items.items())
         required = tuple(sorted(typ.required_keys))
         readonly = tuple(sorted(typ.readonly_keys))
-        return ("TypedDictType", items, required, readonly)
+        return ("TypedDictType", items, required, readonly, typ.is_closed)
 
     def visit_literal_type(self, typ: LiteralType) -> SnapshotItem:
         return ("LiteralType", snapshot_type(typ.fallback), typ.value)

test-data/unit/diff.test

@@ -676,6 +676,24 @@ p = Point(dict(x=42, y=1337))
 __main__.Point
 __main__.p
 
+[case testTypedDict5]
+from typing import TypedDict
+class Point(TypedDict):
+    x: int
+    y: int
+p = Point(dict(x=42, y=1337))
+[file next.py]
+from typing import TypedDict
+class Point(TypedDict, closed=True):
+    x: int
+    y: int
+p = Point(dict(x=42, y=1337))
+[builtins fixtures/dict.pyi]
+[typing fixtures/typing-typeddict.pyi]
+[out]
+__main__.Point
+__main__.p
+
 [case testTypeAliasSimple]
 A = int
 B = int

test-data/unit/fine-grained.test

@@ -3745,6 +3745,49 @@ b.py:4: error: ReadOnly TypedDict key "y" TypedDict is mutated
 ==
 b.py:3: error: ReadOnly TypedDict key "x" TypedDict is mutated
 
+[case testTypedDictUpdateClosed]
+import b
+[file a.py]
+from typing import TypedDict, Union
+class A(TypedDict):
+  a: int
+class B(TypedDict, closed=True):
+  b: int
+C = Union[A, B]
+[file a.py.2]
+from typing import TypedDict, Union
+class A(TypedDict, closed=True):
+  a: int
+class B(TypedDict):
+  b: int
+C = Union[A, B]
+[file a.py.3]
+from typing import TypedDict, Union
+class A(TypedDict, closed=True):
+  a: int
+class B(TypedDict, closed=True):
+  b: int
+C = Union[A, B]
+[file b.py]
+from a import C
+def foo(x: C) -> int:
+    if "b" in x:
+       return x["b"]
+    else:
+       return x["a"]
+def bar(x: C) -> int:
+    if "a" in x:
+       return x["a"]
+    else:
+       return x["b"]
+[builtins fixtures/dict.pyi]
+[typing fixtures/typing-typeddict.pyi]
+[out]
+b.py:4: error: TypedDict "A" has no key "b"
+==
+b.py:9: error: TypedDict "B" has no key "a"
+==
+
 [case testBasicAliasUpdate]
 import b
 [file a.py]