To avoid data leak, test set should start from numForecastDays later

ai/training_data_builder.py

@@ -200,5 +200,5 @@ class TrainingDataBuilder(ABC):
             # To avoid data leak, test set should start from numForecastDays later
             X_test = X_test[self._numForecastDays:]
             y_test = y_test[self._numForecastDays:]
-            date_index = DataAll['date'][:-len(X_test)].to_numpy()
+            date_index = DataAll['date'][-len(X_test):].to_numpy()
         return X_train, X_test, y_train, y_test, scaledX_forecast, forecastDay, date_index