Use a seperate database for tests

Author: JohnTheGood

backend/app/constants.py

@@ -1,3 +1,4 @@
 from pathlib import Path
 
 APP_PATH = Path(__file__).parent
+BACKEND_PATH = APP_PATH.parent

backend/tests/conftest.py

@@ -2,33 +2,77 @@
 
 import pytest
 from fastapi.testclient import TestClient
-from sqlmodel import Session, delete
+from pydantic_core import MultiHostUrl
+from sqlalchemy import text
+from sqlmodel import Session, create_engine
 
+from app.auth.dependencies import get_db
 from app.config import settings
-from app.database import engine, init_db
-from app.items.models import Item
+from app.database import init_db
 from app.main import app
-from app.users.models import User
 from tests.utils.user import authentication_token_from_email
 from tests.utils.utils import get_superuser_token_headers
 
+TEST_POSTGRES_DB = settings.POSTGRES_DB + "_test"
+
+TEST_DATABASE_URI = MultiHostUrl.build(
+    scheme="postgresql+psycopg",
+    username=settings.POSTGRES_USER,
+    password=settings.POSTGRES_PASSWORD,
+    host=settings.POSTGRES_SERVER,
+    port=settings.POSTGRES_PORT,
+    path=TEST_POSTGRES_DB,
+)
+
+test_engine = create_engine(str(TEST_DATABASE_URI))
+
+
+ADMIN_DATABASE_URI = MultiHostUrl.build(
+    scheme="postgresql+psycopg",
+    username=settings.POSTGRES_USER,
+    password=settings.POSTGRES_PASSWORD,
+    host=settings.POSTGRES_SERVER,
+    port=settings.POSTGRES_PORT,
+    path="postgres",
+)
+
+admin_engine = create_engine(str(ADMIN_DATABASE_URI))
+
+
+def create_test_database() -> None:
+    """Create the test database by copying the existing database."""
+    # AUTOCOMMIT is required to drop a database
+    with admin_engine.connect().execution_options(isolation_level="AUTOCOMMIT") as conn:
+        conn.execute(text(f'DROP DATABASE IF EXISTS "{TEST_POSTGRES_DB}"'))
+        conn.execute(
+            text(
+                f'CREATE DATABASE "{TEST_POSTGRES_DB}" WITH TEMPLATE "{settings.POSTGRES_DB}"',
+            ),
+        )
+
 
 @pytest.fixture(scope="session", autouse=True)
-def db() -> Generator[Session, None, None]:
-    with Session(engine) as session:
+def db() -> Generator[Session]:
+    create_test_database()
+    with Session(test_engine) as session:
         init_db(session)
         yield session
-        statement = delete(Item)
-        session.execute(statement)
-        statement = delete(User)
-        session.execute(statement)
-        session.commit()
+    with admin_engine.connect().execution_options(isolation_level="AUTOCOMMIT") as conn:
+        conn.execute(text(f'DROP DATABASE IF EXISTS "{TEST_POSTGRES_DB}"'))
+
+
+def get_test_db() -> Generator[Session]:
+    """Database dependency override for testing."""
+    with Session(test_engine) as session:
+        yield session
 
 
 @pytest.fixture(scope="module")
-def client() -> Generator[TestClient, None, None]:
+def client() -> Generator[TestClient]:
+    app.dependency_overrides[get_db] = get_test_db
     with TestClient(app) as c:
         yield c
+    app.dependency_overrides.clear()
 
 
 @pytest.fixture(scope="module")
@@ -39,5 +83,7 @@ def superuser_token_headers(client: TestClient) -> dict[str, str]:
 @pytest.fixture(scope="module")
 def normal_user_token_headers(client: TestClient, db: Session) -> dict[str, str]:
     return authentication_token_from_email(
-        client=client, email=settings.EMAIL_TEST_USER, db=db
+        client=client,
+        email=settings.EMAIL_TEST_USER,
+        db=db,
     )