pep-484: session, instancestate, etc

Also adds some fixes to annotation-based mapping
that have come up, as well as starts to add more
pep-484 test cases

Change-Id: Ia722bbbc7967a11b23b66c8084eb61df9d233fee

1 files changed, 50 insertions, 0 deletions

diff --git a/test/ext/mypy/plain_files/session.py b/test/ext/mypy/plain_files/session.py
new file mode 100644
index 000000000..24c685e84
--- /dev/null
+++ b/test/ext/mypy/plain_files/session.py
@@ -0,0 +1,50 @@
+from __future__ import annotations
+
+from typing import List
+from typing import Sequence
+
+from sqlalchemy import create_engine
+from sqlalchemy import ForeignKey
+from sqlalchemy import select
+from sqlalchemy.orm import DeclarativeBase
+from sqlalchemy.orm import Mapped
+from sqlalchemy.orm import mapped_column
+from sqlalchemy.orm import relationship
+from sqlalchemy.orm import Session
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+class User(Base):
+    __tablename__ = "user"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    name: Mapped[str]
+    addresses: Mapped[List[Address]] = relationship(back_populates="user")
+
+
+class Address(Base):
+    __tablename__ = "address"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    user_id = mapped_column(ForeignKey("user.id"))
+    email: Mapped[str]
+
+    user: Mapped[User] = relationship(back_populates="addresses")
+
+
+e = create_engine("sqlite://")
+Base.metadata.create_all(e)
+
+with Session(e) as sess:
+    u1 = User(name="u1")
+    sess.add(u1)
+    sess.add_all([Address(user=u1, email="e1"), Address(user=u1, email="e2")])
+    sess.commit()
+
+with Session(e) as sess:
+    users: Sequence[User] = sess.scalars(
+        select(User), execution_options={"stream_results": False}
+    ).all()