[ty] Prepare test files for reachability changes (astral-sh#24207)

## Summary

Some mdtest changes in preparation for
astral-sh#23245.

Author: sharkdp

crates/ty_python_semantic/resources/mdtest/call/getattr_static.md

@@ -47,8 +47,9 @@ When a non-existent attribute is accessed without a default value, the runtime r
 `AttributeError`. We could emit a diagnostic for this case, but that is currently not supported:
 
 ```py
-# TODO: we could emit a diagnostic here
-reveal_type(inspect.getattr_static(C, "non_existent"))  # revealed: Never
+def _():
+    # TODO: we could emit a diagnostic here
+    reveal_type(inspect.getattr_static(C, "non_existent"))  # revealed: Never
 ```
 
 We can access attributes on objects of all kinds:

crates/ty_python_semantic/resources/mdtest/narrow/match.md

@@ -294,24 +294,16 @@ def _(x: Literal["foo", b"bar"] | int):
 ## Narrowing due to guard
 
 ```py
-def get_object() -> object:
-    return object()
-
-x = get_object()
-
-reveal_type(x)  # revealed: object
-
-match x:
-    case str() | float() if type(x) is str:
-        reveal_type(x)  #  revealed: str
-    case "foo" | 42 | None if isinstance(x, int):
-        reveal_type(x)  #  revealed: int
-    case False if x:
-        reveal_type(x)  #  revealed: Never
-    case "foo" if x := "bar":
-        reveal_type(x)  # revealed: Literal["bar"]
-
-reveal_type(x)  # revealed: object
+def _(x: object):
+    match x:
+        case str() | float() if type(x) is str:
+            reveal_type(x)  #  revealed: str
+        case "foo" | 42 | None if isinstance(x, int):
+            reveal_type(x)  #  revealed: int
+        case False if x:
+            reveal_type(x)  #  revealed: Never
+        case "foo" if x := "bar":
+            reveal_type(x)  # revealed: Literal["bar"]
 ```
 
 ## Guard and reveal_type in guard

crates/ty_python_semantic/resources/mdtest/narrow/post_if_statement.md

@@ -256,3 +256,16 @@ async def main(val: int | None):
         await stop()
     reveal_type(val)  # revealed: int
 ```
+
+## Narrowing in global scope
+
+```py
+data: dict[str, str] = {}
+api_key = data.get("api_key")
+
+if not api_key:
+    exit(1)
+
+# TODO: Should be str & ~AlwaysFalsy
+reveal_type(api_key)  # revealed: str | None
+```

crates/ty_python_semantic/resources/mdtest/narrow/truthiness.md

@@ -3,47 +3,51 @@
 ## Value Literals
 
 ```py
-from typing import Literal
-
-def foo() -> Literal[0, -1, True, False, "", "foo", b"", b"bar", None] | tuple[()]:
-    return 0
+from typing import Literal, TypeAlias
 
-x = foo()
+X: TypeAlias = Literal[0, -1, True, False, "", "foo", b"", b"bar", None] | tuple[()]
 
-if x:
-    reveal_type(x)  # revealed: Literal[-1, True, "foo", b"bar"]
-else:
-    reveal_type(x)  # revealed: Literal[0, False, "", b""] | None | tuple[()]
+def _(x: X):
+    if x:
+        reveal_type(x)  # revealed: Literal[-1, True, "foo", b"bar"]
+    else:
+        reveal_type(x)  # revealed: Literal[0, False, "", b""] | None | tuple[()]
 
-if not x:
-    reveal_type(x)  # revealed: Literal[0, False, "", b""] | None | tuple[()]
-else:
-    reveal_type(x)  # revealed: Literal[-1, True, "foo", b"bar"]
+def _(x: X):
+    if not x:
+        reveal_type(x)  # revealed: Literal[0, False, "", b""] | None | tuple[()]
+    else:
+        reveal_type(x)  # revealed: Literal[-1, True, "foo", b"bar"]
 
-if x and not x:
-    reveal_type(x)  # revealed: Never
-else:
-    reveal_type(x)  # revealed: Literal[0, -1, "", "foo", b"", b"bar"] | bool | None | tuple[()]
+def _(x: X):
+    if x and not x:
+        reveal_type(x)  # revealed: Never
+    else:
+        reveal_type(x)  # revealed: Literal[0, -1, "", "foo", b"", b"bar"] | bool | None | tuple[()]
 
-if not (x and not x):
-    reveal_type(x)  # revealed: Literal[0, -1, "", "foo", b"", b"bar"] | bool | None | tuple[()]
-else:
-    reveal_type(x)  # revealed: Never
+def _(x: X):
+    if not (x and not x):
+        reveal_type(x)  # revealed: Literal[0, -1, "", "foo", b"", b"bar"] | bool | None | tuple[()]
+    else:
+        reveal_type(x)  # revealed: Never
 
-if x or not x:
-    reveal_type(x)  # revealed: Literal[-1, 0, "foo", "", b"bar", b""] | bool | None | tuple[()]
-else:
-    reveal_type(x)  # revealed: Never
+def _(x: X):
+    if x or not x:
+        reveal_type(x)  # revealed: Literal[-1, 0, "foo", "", b"bar", b""] | bool | None | tuple[()]
+    else:
+        reveal_type(x)  # revealed: Never
 
-if not (x or not x):
-    reveal_type(x)  # revealed: Never
-else:
-    reveal_type(x)  # revealed: Literal[-1, 0, "foo", "", b"bar", b""] | bool | None | tuple[()]
+def _(x: X):
+    if not (x or not x):
+        reveal_type(x)  # revealed: Never
+    else:
+        reveal_type(x)  # revealed: Literal[-1, 0, "foo", "", b"bar", b""] | bool | None | tuple[()]
 
-if (isinstance(x, int) or isinstance(x, str)) and x:
-    reveal_type(x)  # revealed: Literal[-1, True, "foo"]
-else:
-    reveal_type(x)  # revealed: Literal[b"", b"bar", 0, False, ""] | None | tuple[()]
+def _(x: X):
+    if (isinstance(x, int) or isinstance(x, str)) and x:
+        reveal_type(x)  # revealed: Literal[-1, True, "foo"]
+    else:
+        reveal_type(x)  # revealed: Literal[b"", b"bar", 0, False, ""] | None | tuple[()]
 ```
 
 ## Walrus Member Access