An issue when calculating profit using TopkDropoutStrategy.

This is a potential issue when calculating profit. https://github.com/microsoft/qlib/blob/main/qlib/backtest/account.py#L194, when you calculate the total profit, you are using the price from last step(which is calculating the day profit), instead of the price where you place you order. Since you update the price after every step https://github.com/microsoft/qlib/blob/main/qlib/backtest/account.py#L245, so you actually overwrite the deal price always with the latest price.

e.g. say you place order at step 2, and close order at step 10, you actually get the profit from step 9 -10, instead of 2 - 10. Because you only calculate profit when you call https://github.com/microsoft/qlib/blob/main/qlib/backtest/executor.py#L604, but you update the price for holding stock for every step.

Read qlib/backtest/account.py around lines 194 and 245, then trace the calculation from qlib/backtest/executor.py around line 604. Reproduce the step-2 entry and step-10 close scenario and verify whether profit uses the order price across the holding period. Done means the calculation reflects the entry-to-exit movement rather than only the final step, with regression coverage for this scenario.