Add checkpoint tests

Author: MDUYN

tests/app/backtesting/test_strategy_saving.py

@@ -1 +1 @@
-{"backtest_start_date": "2023-08-07 05:00:00", "backtest_date_range_name": "Test Backtest Date Range", "backtest_end_date": "2023-12-01 23:00:00", "trading_symbol": "EUR", "initial_unallocated": 1000, "number_of_runs": 1000, "portfolio_snapshots": [{"metadata": {}, "portfolio_id": "", "trading_symbol": "EUR", "pending_value": 0.0, "unallocated": 1000, "total_net_gain": 0.0, "total_revenue": 0.0, "total_cost": 0.0, "cash_flow": 0.0, "net_size": 0.0, "created_at": "2023-08-07T07:00:00+00:00", "total_value": 1000}, {"metadata": {}, "portfolio_id": "", "trading_symbol": "EUR", "pending_value": 0.0, "unallocated": 200, "total_net_gain": 0.0, "total_revenue": 0.0, "total_cost": 0.0, "cash_flow": 0.0, "net_size": 0.0, "created_at": "2023-12-02T00:00:00+00:00", "total_value": 1200}], "trades": [], "orders": [], "positions": [], "created_at": "2025-12-26 11:56:03", "symbols": [], "number_of_days": 0, "number_of_trades": 0, "number_of_trades_closed": 0, "number_of_trades_open": 0, "number_of_orders": 0, "number_of_positions": 0, "metadata": {}}
+{"backtest_start_date": "2023-08-07 05:00:00", "backtest_date_range_name": "Test Backtest Date Range", "backtest_end_date": "2023-12-01 23:00:00", "trading_symbol": "EUR", "initial_unallocated": 1000, "number_of_runs": 1000, "portfolio_snapshots": [{"metadata": {}, "portfolio_id": "", "trading_symbol": "EUR", "pending_value": 0.0, "unallocated": 1000, "total_net_gain": 0.0, "total_revenue": 0.0, "total_cost": 0.0, "cash_flow": 0.0, "net_size": 0.0, "created_at": "2023-08-07T07:00:00+00:00", "total_value": 1000}, {"metadata": {}, "portfolio_id": "", "trading_symbol": "EUR", "pending_value": 0.0, "unallocated": 200, "total_net_gain": 0.0, "total_revenue": 0.0, "total_cost": 0.0, "cash_flow": 0.0, "net_size": 0.0, "created_at": "2023-12-02T00:00:00+00:00", "total_value": 1200}], "trades": [], "orders": [], "positions": [], "created_at": "2025-12-28 06:01:10", "symbols": [], "number_of_days": 0, "number_of_trades": 0, "number_of_trades_closed": 0, "number_of_trades_open": 0, "number_of_orders": 0, "number_of_positions": 0, "metadata": {}}