Fix tests on 3.13.0a5 (#358)

CHANGELOG.md

@@ -1,5 +1,6 @@
 # Unreleased
 
+- Fix tests on 3.13.0a5. Patch by Jelle Zijlstra.
 - Fix the runtime behavior of type parameters with defaults (PEP 696).
   Patch by Nadir Chowdhury.
 - Fix minor discrepancy between error messages produced by `typing`

src/test_typing_extensions.py

@@ -5531,7 +5531,7 @@ def test_typing_extensions_defers_when_possible(self):
             }
         if sys.version_info < (3, 13):
             exclude |= {'NamedTuple', 'Protocol', 'runtime_checkable'}
-        if not hasattr(typing, 'ReadOnly'):
+        if not typing_extensions._PEP_728_IMPLEMENTED:
             exclude |= {'TypedDict', 'is_typeddict'}
         for item in typing_extensions.__all__:
             if item not in exclude and hasattr(typing, item):

src/typing_extensions.py

@@ -792,7 +792,11 @@ def inner(func):
     return inner
 
 
-if hasattr(typing, "ReadOnly"):
+# Update this to something like >=3.13.0b1 if and when
+# PEP 728 is implemented in CPython
+_PEP_728_IMPLEMENTED = False
+
+if _PEP_728_IMPLEMENTED:
     # The standard library TypedDict in Python 3.8 does not store runtime information
     # about which (if any) keys are optional.  See https://bugs.python.org/issue38834
     # The standard library TypedDict in Python 3.9.0/1 does not honour the "total"
@@ -803,7 +807,8 @@ def inner(func):
     # Aaaand on 3.12 we add __orig_bases__ to TypedDict
     # to enable better runtime introspection.
     # On 3.13 we deprecate some odd ways of creating TypedDicts.
-    # PEP 705 proposes adding the ReadOnly[] qualifier.
+    # Also on 3.13, PEP 705 adds the ReadOnly[] qualifier.
+    # PEP 728 (still pending) makes more changes.
     TypedDict = typing.TypedDict
     _TypedDictMeta = typing._TypedDictMeta
     is_typeddict = typing.is_typeddict