Use in memory databases for testing

tests/conftest.py

@@ -19,6 +19,10 @@ import app.database as database
 def client() -> TestClient:
     return TestClient(app)
 
+
 @pytest.fixture
 def db_connection():
-    return database.connect("test.sqlite3")
+    connection = database.connect(":memory:")
+    database.apply_database_schema(connection)
+    yield connection
+    connection.close()

tests/database_test.py

@@ -5,8 +5,6 @@ from app.types import Order, OrderSide, OrderType
 
 
 def test_store_order(db_connection):
-    database.apply_database_schema(db_connection)
-
     order = Order(
         id="",
         created_at=datetime.now(),