use jsonschema regex pattern for whitelist format and enhance validation error messages (closes #120)

freqtrade/misc.py

@@ -6,7 +6,8 @@ import os
 import time
 from typing import Any, Callable, List, Dict
 
-from jsonschema import validate
+from jsonschema import validate, Draft4Validator
+from jsonschema.exceptions import best_match, ValidationError
 from wrapt import synchronized
 
 from freqtrade import __version__
@@ -58,8 +59,14 @@ def load_config(path: str) -> Dict:
     if 'internals' not in conf:
         conf['internals'] = {}
     logger.info('Validating configuration ...')
-    validate(conf, CONF_SCHEMA)
-    return conf
+    try:
+        validate(conf, CONF_SCHEMA)
+        return conf
+    except ValidationError:
+        logger.fatal('Configuration is not valid! See config.json.example')
+        raise ValidationError(
+            best_match(Draft4Validator(CONF_SCHEMA).iter_errors(conf)).message
+        )
 
 
 def throttle(func: Callable[..., Any], min_secs: float, *args, **kwargs) -> Any:
@@ -218,7 +225,10 @@ CONF_SCHEMA = {
                 'secret': {'type': 'string'},
                 'pair_whitelist': {
                     'type': 'array',
-                    'items': {'type': 'string'},
+                    'items': {
+                        'type': 'string',
+                        'pattern': '^[0-9A-Z]+_[0-9A-Z]+$'
+                    },
                     'uniqueItems': True
                 }
             },

freqtrade/tests/test_misc.py

@@ -1,12 +1,15 @@
 # pragma pylint: disable=missing-docstring,C0103
-import time
+import json
 import os
+import time
 from argparse import Namespace
+from copy import deepcopy
 from unittest.mock import MagicMock
 
 import pytest
+from jsonschema import ValidationError
 
-from freqtrade.misc import throttle, parse_args, start_backtesting
+from freqtrade.misc import throttle, parse_args, start_backtesting, load_config
 
 
 def test_throttle():
@@ -119,3 +122,28 @@ def test_start_backtesting(mocker):
     main_call_args = pytest_mock.call_args[0][0]
     assert main_call_args[0] == '-s'
     assert main_call_args[1].endswith(os.path.join('freqtrade', 'tests', 'test_backtesting.py'))
+
+
+def test_load_config(default_conf, mocker):
+    file_mock = mocker.patch('freqtrade.misc.open', mocker.mock_open(
+        read_data=json.dumps(default_conf)
+    ))
+    validated_conf = load_config('somefile')
+    assert file_mock.call_count == 1
+    assert validated_conf.items() >= default_conf.items()
+
+
+def test_load_config_invalid_pair(default_conf, mocker):
+    conf = deepcopy(default_conf)
+    conf['exchange']['pair_whitelist'].append('BTC-ETH')
+    mocker.patch('freqtrade.misc.open', mocker.mock_open(read_data=json.dumps(conf)))
+    with pytest.raises(ValidationError, match=r'.*does not match.*'):
+        load_config('somefile')
+
+
+def test_load_config_missing_attributes(default_conf, mocker):
+    conf = deepcopy(default_conf)
+    conf.pop('exchange')
+    mocker.patch('freqtrade.misc.open', mocker.mock_open(read_data=json.dumps(conf)))
+    with pytest.raises(ValidationError, match=r'.*\'exchange\' is a required property.*'):
+        load_config('somefile')