Use the new FastAPI lifespan hook

Rather than using startup and shutdown events, use the new FastAPI
lifespan hook and async context manager. This avoids warnings while
running the test suite.

src/gafaelfawr/main.py

@@ -3,6 +3,8 @@
 from __future__ import annotations
 
 import os
+from collections.abc import AsyncIterator, Coroutine
+from contextlib import asynccontextmanager
 from importlib.metadata import version
 from pathlib import Path
 
@@ -31,7 +33,11 @@
 __all__ = ["create_app"]
 
 
-def create_app(*, load_config: bool = True) -> FastAPI:
+def create_app(
+    *,
+    load_config: bool = True,
+    extra_startup: Coroutine[None, None, None] | None = None,
+) -> FastAPI:
     """Create the FastAPI application.
 
     This is in a function rather than using a global variable (as is more
@@ -46,7 +52,27 @@ def create_app(*, load_config: bool = True) -> FastAPI:
         set of proxy IP addresses.  This is used primarily for OpenAPI
         schema generation, where constructing the app is required but the
         configuration won't matter.
+    extra_startup
+        If provided, an additional coroutine to run as part of the startup
+        section of the lifespan context manager, used by the test suite.
     """
+
+    @asynccontextmanager
+    async def lifespan(app: FastAPI) -> AsyncIterator[None]:
+        config = config_dependency.config()
+        await context_dependency.initialize(config)
+        await db_session_dependency.initialize(
+            config.database_url, config.database_password
+        )
+        if extra_startup:
+            await extra_startup
+
+        yield
+
+        await http_client_dependency.aclose()
+        await db_session_dependency.aclose()
+        await context_dependency.aclose()
+
     app = FastAPI(
         title="Gafaelfawr",
         description=(
@@ -83,6 +109,7 @@ def create_app(*, load_config: bool = True) -> FastAPI:
         openapi_url="/auth/openapi.json",
         docs_url="/auth/docs",
         redoc_url="/auth/redoc",
+        lifespan=lifespan,
     )
 
     # Add all of the routes.
@@ -143,20 +170,6 @@ def create_app(*, load_config: bool = True) -> FastAPI:
     # Handle exceptions descended from ClientRequestError.
     app.exception_handler(ClientRequestError)(client_request_error_handler)
 
-    @app.on_event("startup")
-    async def startup_event() -> None:
-        config = config_dependency.config()
-        await context_dependency.initialize(config)
-        await db_session_dependency.initialize(
-            config.database_url, config.database_password
-        )
-
-    @app.on_event("shutdown")
-    async def shutdown_event() -> None:
-        await http_client_dependency.aclose()
-        await db_session_dependency.aclose()
-        await context_dependency.aclose()
-
     # This is a temporary workaround for a bug in FastAPI handling Pydantic
     # validation errors when a list query parameter is not specified. See
     # https://github.com/tiangolo/fastapi/issues/9920

tests/support/selenium.py

@@ -128,14 +128,12 @@ def selenium_create_app() -> FastAPI:
     be called by uvicorn in the separate process spawned by run_app.  If it is
     run in the main pytest process, it will break other tests.
     """
-    app = create_app()
     token_path = Path(os.environ["GAFAELFAWR_TEST_TOKEN_PATH"])
 
-    @app.on_event("startup")
-    async def selenium_startup_event() -> None:
+    async def selenium_startup() -> None:
         await _selenium_startup(token_path)
 
-    return app
+    return create_app(extra_startup=selenium_startup())
 
 
 @asynccontextmanager