Add test to ensure configuration error is displayed as expected

tests/test_main.py

@@ -8,7 +8,7 @@ import pytest
 
 from freqtrade.commands import Arguments
 from freqtrade.enums import State
-from freqtrade.exceptions import FreqtradeException, OperationalException
+from freqtrade.exceptions import ConfigurationError, FreqtradeException, OperationalException
 from freqtrade.freqtradebot import FreqtradeBot
 from freqtrade.main import main
 from freqtrade.worker import Worker
@@ -141,6 +141,22 @@ def test_main_operational_exception1(mocker, default_conf, caplog) -> None:
     assert log_has_re(r'SIGINT.*', caplog)
 
 
+def test_main_ConfigurationError(mocker, default_conf, caplog) -> None:
+    patch_exchange(mocker)
+    mocker.patch(
+        'freqtrade.commands.list_commands.list_available_exchanges',
+        MagicMock(side_effect=ConfigurationError('Oh snap!'))
+    )
+    patched_configuration_load_config_file(mocker, default_conf)
+
+    args = ['list-exchanges']
+
+    # Test Main + the KeyboardInterrupt exception
+    with pytest.raises(SystemExit):
+        main(args)
+    assert log_has_re('Configuration error: Oh snap!', caplog)
+
+
 def test_main_reload_config(mocker, default_conf, caplog) -> None:
     patch_exchange(mocker)
     mocker.patch('freqtrade.freqtradebot.FreqtradeBot.cleanup', MagicMock())