Rename Red Knot (#17820)

crates/ty_python_semantic/resources/mdtest/subscript/class.md

@@ -0,0 +1,86 @@
+# Class subscript
+
+## Class getitem unbound
+
+```py
+class NotSubscriptable: ...
+
+a = NotSubscriptable[0]  # error: "Cannot subscript object of type `Literal[NotSubscriptable]` with no `__class_getitem__` method"
+```
+
+## Class getitem
+
+```py
+class Identity:
+    def __class_getitem__(cls, item: int) -> str:
+        return str(item)
+
+reveal_type(Identity[0])  # revealed: str
+```
+
+## Class getitem union
+
+```py
+def _(flag: bool):
+    class UnionClassGetItem:
+        if flag:
+            def __class_getitem__(cls, item: int) -> str:
+                return str(item)
+        else:
+            def __class_getitem__(cls, item: int) -> int:
+                return item
+
+    reveal_type(UnionClassGetItem[0])  # revealed: str | int
+```
+
+## Class getitem with class union
+
+```py
+def _(flag: bool):
+    class A:
+        def __class_getitem__(cls, item: int) -> str:
+            return str(item)
+
+    class B:
+        def __class_getitem__(cls, item: int) -> int:
+            return item
+
+    x = A if flag else B
+
+    reveal_type(x)  # revealed: Literal[A, B]
+    reveal_type(x[0])  # revealed: str | int
+```
+
+## Class getitem with unbound method union
+
+```py
+def _(flag: bool):
+    if flag:
+        class Spam:
+            def __class_getitem__(self, x: int) -> str:
+                return "foo"
+
+    else:
+        class Spam: ...
+    # error: [call-possibly-unbound-method] "Method `__class_getitem__` of type `Literal[Spam, Spam]` is possibly unbound"
+    # revealed: str
+    reveal_type(Spam[42])
+```
+
+## TODO: Class getitem non-class union
+
+```py
+def _(flag: bool):
+    if flag:
+        class Eggs:
+            def __class_getitem__(self, x: int) -> str:
+                return "foo"
+
+    else:
+        Eggs = 1
+
+    a = Eggs[42]  # error: "Cannot subscript object of type `Literal[Eggs] | Literal[1]` with no `__getitem__` method"
+
+    # TODO: should _probably_ emit `str | Unknown`
+    reveal_type(a)  # revealed: Unknown
+```