fix chapter 6 ruff errors without changing behavior

Modernize type annotations and the UTC alias, and mark the unused lifespan parameter explicitly.

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Co-authored-by: Snowflake CoCo <noreply@snowflake.com>

Author: svnv-svsv-jm

Chapter06/registration-service/alembic/versions/21e17247292d_add_user_preferences.py

@@ -6,7 +6,7 @@
 
 """
 
-from typing import Sequence, Union
+from collections.abc import Sequence
 
 import sqlalchemy as sa
 from sqlalchemy.dialects import postgresql
@@ -15,9 +15,9 @@
 
 # revision identifiers, used by Alembic.
 revision: str = "21e17247292d"
-down_revision: Union[str, Sequence[str], None] = "911c97e9e02f"
-branch_labels: Union[str, Sequence[str], None] = None
-depends_on: Union[str, Sequence[str], None] = None
+down_revision: str | Sequence[str] | None = "911c97e9e02f"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
 
 
 def upgrade() -> None:

Chapter06/registration-service/alembic/versions/911c97e9e02f_create_users_table.py

@@ -6,17 +6,17 @@
 
 """
 
-from typing import Sequence, Union
+from collections.abc import Sequence
 
 import sqlalchemy as sa
 
 from alembic import op
 
 # revision identifiers, used by Alembic.
 revision: str = "911c97e9e02f"
-down_revision: Union[str, Sequence[str], None] = None
-branch_labels: Union[str, Sequence[str], None] = None
-depends_on: Union[str, Sequence[str], None] = None
+down_revision: str | Sequence[str] | None = None
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
 
 
 def upgrade() -> None:

Chapter06/registration-service/database.py

@@ -25,6 +25,6 @@
 )
 
 
-async def get_db() -> AsyncGenerator[AsyncSession, None]:
+async def get_db() -> AsyncGenerator[AsyncSession]:
     async with async_session() as session:
         yield session

Chapter06/registration-service/main.py

@@ -14,7 +14,7 @@
 
 
 @asynccontextmanager
-async def lifespan(app: FastAPI) -> AsyncGenerator[None, None]:
+async def lifespan(_app: FastAPI) -> AsyncGenerator[None]:
     yield
     await engine.dispose()
 

Chapter06/registration-service/models.py

@@ -1,4 +1,4 @@
-from datetime import datetime, timezone
+from datetime import UTC, datetime
 
 from sqlalchemy import JSON, Boolean, DateTime, Integer, String
 from sqlalchemy.dialects.postgresql import JSONB
@@ -43,7 +43,7 @@ class User(Base):
     )
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True),
-        default=lambda: datetime.now(timezone.utc),
+        default=lambda: datetime.now(UTC),
     )
 
     preferences: Mapped[dict | None] = mapped_column(

Chapter06/registration-service/test_main.py

@@ -33,7 +33,7 @@
 )
 
 
-async def override_get_db() -> AsyncGenerator[AsyncSession, None]:
+async def override_get_db() -> AsyncGenerator[AsyncSession]:
     async with session_factory() as session:
         yield session
 
@@ -42,7 +42,7 @@ async def override_get_db() -> AsyncGenerator[AsyncSession, None]:
 
 
 @pytest.fixture(autouse=True)
-def database() -> Generator[None, None, None]:
+def database() -> Generator[None]:
     Base.metadata.create_all(schema_engine)
     yield
     Base.metadata.drop_all(schema_engine)