feat: validate demo-trading and dry-run incompatibility

freqtrade/configuration/config_validation.py

@@ -92,6 +92,7 @@ def validate_config_consistency(conf: dict[str, Any], *, preliminary: bool = Fal
     _validate_consumers(conf)
     validate_migrated_strategy_settings(conf)
     _validate_orderflow(conf)
+    _validate_demo_trading(conf)
 
     # validate configuration before returning
     logger.info("Validating configuration ...")
@@ -413,6 +414,11 @@ def _validate_orderflow(conf: dict[str, Any]) -> None:
             )
 
 
+def _validate_demo_trading(conf: dict[str, Any]) -> None:
+    if conf.get("exchange", {}).get("demo_trading", False) and conf.get("dry_run", False):
+        raise ConfigurationError("Demo trading cannot be used together with dry_run.")
+
+
 def _strategy_settings(conf: dict[str, Any]) -> None:
     process_deprecated_setting(conf, None, "use_sell_signal", None, "use_exit_signal")
     process_deprecated_setting(conf, None, "sell_profit_only", None, "exit_profit_only")