Add additional test

freqtrade/configuration/load_config.py

@@ -29,8 +29,11 @@ def log_config_error_range(path: str, errmsg: str) -> str:
             # Fetch an offset of 80 characters around the error line
             subtext = text[offset-min(80, offset):offset+80]
             segments = subtext.split('\n')
-            # Remove first and last lines, to avoid odd truncations
-            return '\n'.join(segments[1:-1])
+            if len(segments) > 3:
+                # Remove first and last lines, to avoid odd truncations
+                return '\n'.join(segments[1:-1])
+            else:
+                return subtext
 
 
 def load_config_file(path: str) -> Dict[str, Any]:

tests/test_configuration.py

@@ -18,7 +18,7 @@ from freqtrade.configuration.config_validation import validate_config_schema
 from freqtrade.configuration.deprecated_settings import (
     check_conflicting_settings, process_deprecated_setting,
     process_temporary_deprecated_settings)
-from freqtrade.configuration.load_config import load_config_file
+from freqtrade.configuration.load_config import load_config_file, log_config_error_range
 from freqtrade.constants import DEFAULT_DB_DRYRUN_URL, DEFAULT_DB_PROD_URL
 from freqtrade.exceptions import OperationalException
 from freqtrade.loggers import _set_loggers, setup_logging
@@ -77,6 +77,19 @@ def test_load_config_file_error(default_conf, mocker, caplog) -> None:
         load_config_file('somefile')
 
 
+def test_load_config_file_error_range(default_conf, mocker, caplog) -> None:
+    del default_conf['user_data_dir']
+    filedata = json.dumps(default_conf).replace(
+        '"stake_amount": 0.001,', '"stake_amount": .001,')
+    mocker.patch.object(Path, "read_text", MagicMock(return_value=filedata))
+
+    x = log_config_error_range('somefile', 'Parse error at offset 64: Invalid value.')
+    assert isinstance(x, str)
+    assert (x == '{"max_open_trades": 1, "stake_currency": "BTC", '
+            '"stake_amount": .001, "fiat_display_currency": "USD", '
+            '"ticker_interval": "5m", "dry_run": true, ')
+
+
 def test__args_to_config(caplog):
 
     arg_list = ['trade', '--strategy-path', 'TestTest']