Check annotations as strings for Python 3.10 (#400)

Co-authored-by: Olivier Grisel <olivier.grisel@ensta.org>

.github/workflows/testing.yml

@@ -102,8 +102,8 @@ jobs:
       run: |
         sudo add-apt-repository ppa:deadsnakes/nightly
         sudo apt update
-        sudo apt install python3.9 python3.9-venv python3.9-dev
-        python3.9 -m venv nightly-venv
+        sudo apt install python3.10 python3.10-venv python3.10-dev
+        python3.10 -m venv nightly-venv
         echo "$PWD/nightly-venv/bin" >> $GITHUB_PATH
     - name: Display Python version
       run: python -c "import sys; print(sys.version)"

CHANGES.md

@@ -1,6 +1,12 @@
 1.7.0 (in development)
 ======================
 
+dev
+===
+
+- Support for pickling type annotations on Python 3.10 as per PEP 563:
+  https://www.python.org/dev/peps/pep-0563/
+  ([PR #400](https://github.com/cloudpipe/cloudpickle/pull/400))
 
 1.6.0
 =====

tests/cloudpickle_test.py

@@ -2205,17 +2205,35 @@ def method(self, arg: type_) -> type_:
                         return arg
                 MyClass.__annotations__ = {'attribute': type_}
 
-                def check_annotations(obj, expected_type):
+                def check_annotations(obj, expected_type, expected_type_str):
                     assert obj.__annotations__["attribute"] == expected_type
-                    assert obj.method.__annotations__["arg"] == expected_type
-                    assert (
-                        obj.method.__annotations__["return"] == expected_type
-                    )
+                    if sys.version_info >= (3, 10):
+                        # In Python 3.10, type annotations are stored as strings.
+                        # See PEP 563 for more details:
+                        # https://www.python.org/dev/peps/pep-0563/
+                        assert (
+                            obj.method.__annotations__["arg"]
+                            == expected_type_str
+                        )
+                        assert (
+                            obj.method.__annotations__["return"]
+                            == expected_type_str
+                        )
+                    else:
+                        assert (
+                            obj.method.__annotations__["arg"] == expected_type
+                        )
+                        assert (
+                            obj.method.__annotations__["return"]
+                            == expected_type
+                        )
                     return "ok"
 
                 obj = MyClass()
-                assert check_annotations(obj, type_) == "ok"
-                assert worker.run(check_annotations, obj, type_) == "ok"
+                assert check_annotations(obj, type_, "type_") == "ok"
+                assert (
+                    worker.run(check_annotations, obj, type_, "type_") == "ok"
+                )
 
     def test_generic_extensions_literal(self):
         typing_extensions = pytest.importorskip('typing_extensions')