Add test database configuration and schema creation for testing

tests/conftest.py

@@ -1,10 +1,13 @@
 from collections.abc import AsyncGenerator
+from types import SimpleNamespace
 from typing import Any
 
 import pytest
 from httpx import ASGITransport, AsyncClient
+from sqlalchemy import text
+from sqlalchemy.exc import ProgrammingError
 
-from app.database import engine
+from app.database import engine, test_engine, get_test_db, get_db
 from app.main import app
 from app.models.base import Base
 from app.redis import get_redis
@@ -19,15 +22,46 @@ from app.redis import get_redis
 def anyio_backend(request):
     return request.param
 
+def _create_db(conn) -> None:
+    """Create a database schema if it doesn't exist."""
+    try:
+        conn.execute(text("CREATE DATABASE testdb"))
+    except ProgrammingError:
+        # This might be raised by databases that don't support `IF NOT EXISTS`
+        # and the schema already exists. You can choose to ignore it.
+        pass
+
+
+def _create_db_schema(conn) -> None:
+    """Create a database schema if it doesn't exist."""
+    try:
+        conn.execute(text("CREATE SCHEMA happy_hog"))
+        conn.execute(text("CREATE SCHEMA shakespeare"))
+    except ProgrammingError:
+        # This might be raised by databases that don't support `IF NOT EXISTS`
+        # and the schema already exists. You can choose to ignore it.
+        pass
+
 
 @pytest.fixture(scope="session")
 async def start_db():
-    async with engine.begin() as conn:
+    # The `engine` is configured for the default 'postgres' database.
+    # We connect to it and create the test database.
+    # A transaction block is not used, as CREATE DATABASE cannot run inside it.
+    async with engine.connect() as conn:
+        await conn.execute(text("COMMIT"))  # Ensure we're not in a transaction
+        await conn.run_sync(_create_db)
+
+    # Now, connect to the newly created `testdb` with `test_engine`
+    async with test_engine.begin() as conn:
+        await conn.execute(text("COMMIT"))  # Ensure we're not in a transaction
+        await conn.run_sync(_create_db_schema)
         await conn.run_sync(Base.metadata.drop_all)
         await conn.run_sync(Base.metadata.create_all)
     # for AsyncEngine created in function scope, close and
     # clean-up pooled connections
     await engine.dispose()
+    await test_engine.dispose()
 
 
 @pytest.fixture(scope="session")
@@ -40,5 +74,6 @@ async def client(start_db) -> AsyncGenerator[AsyncClient, Any]:  # noqa: ARG001
         headers={"Content-Type": "application/json"},
         transport=transport,
     ) as test_client:
+        app.dependency_overrides[get_db] = get_test_db
         app.redis = await get_redis()
         yield test_client