Move exception handling to resolver, add test

freqtrade/freqtradebot.py

@@ -17,7 +17,6 @@ from freqtrade import (DependencyException, OperationalException,
 from freqtrade.data.converter import order_book_to_dataframe
 from freqtrade.data.dataprovider import DataProvider
 from freqtrade.edge import Edge
-from freqtrade.exchange import Exchange
 from freqtrade.persistence import Trade
 from freqtrade.rpc import RPCManager, RPCMessageType
 from freqtrade.resolvers import ExchangeResolver, StrategyResolver, PairListResolver
@@ -57,12 +56,7 @@ class FreqtradeBot(object):
         self.rpc: RPCManager = RPCManager(self)
 
         exchange_name = self.config.get('exchange', {}).get('name', 'bittrex').title()
-        try:
+        self.exchange = ExchangeResolver(exchange_name, self.config).exchange
-            self.exchange = ExchangeResolver(exchange_name, self.config).exchange
-        except ImportError:
-            logger.info(
-                f"No {exchange_name} specific subclass found. Using the generic class instead.")
-            self.exchange = Exchange(self.config)
 
         self.wallets = Wallets(self.exchange)
         self.dataprovider = DataProvider(self.config, self.exchange)

freqtrade/resolvers/exchange_resolver.py

@@ -22,7 +22,12 @@ class ExchangeResolver(IResolver):
         Load the custom class from config parameter
         :param config: configuration dictionary or None
         """
-        self.exchange = self._load_exchange(exchange_name, kwargs={'config': config})
+        try:
+            self.exchange = self._load_exchange(exchange_name, kwargs={'config': config})
+        except ImportError:
+            logger.info(
+                f"No {exchange_name} specific subclass found. Using the generic class instead.")
+            self.exchange = Exchange(config)
 
     def _load_exchange(
             self, exchange_name: str, kwargs: dict) -> Exchange:

freqtrade/tests/exchange/test_exchange.py

@@ -13,7 +13,8 @@ from pandas import DataFrame
 
 from freqtrade import DependencyException, OperationalException, TemporaryError
 from freqtrade.exchange import API_RETRY_COUNT, Exchange
-from freqtrade.tests.conftest import get_patched_exchange, log_has
+from freqtrade.tests.conftest import get_patched_exchange, log_has, log_has_re
+from freqtrade.resolvers.exchange_resolver import ExchangeResolver
 
 
 # Source: https://stackoverflow.com/questions/29881236/how-to-mock-asyncio-coroutines
@@ -106,6 +107,23 @@ def test_init_exception(default_conf, mocker):
         Exchange(default_conf)
 
 
+def test_exchange_resolver(default_conf, mocker, caplog):
+    mocker.patch('freqtrade.exchange.Exchange._init_ccxt', MagicMock(return_value=MagicMock()))
+    mocker.patch('freqtrade.exchange.Exchange._load_async_markets', MagicMock())
+    mocker.patch('freqtrade.exchange.Exchange.validate_pairs', MagicMock())
+    mocker.patch('freqtrade.exchange.Exchange.validate_timeframes', MagicMock())
+    exchange = ExchangeResolver('Binance', default_conf).exchange
+    assert isinstance(exchange, Exchange)
+    assert log_has_re(r"No .* specific subclass found. Using the generic class instead.",
+                      caplog.record_tuples)
+    caplog.clear()
+
+    exchange = ExchangeResolver('Kraken', default_conf).exchange
+    assert isinstance(exchange, Exchange)
+    assert not log_has_re(r"No .* specific subclass found. Using the generic class instead.",
+                          caplog.record_tuples)
+
+
 def test_symbol_amount_prec(default_conf, mocker):
     '''
     Test rounds down to 4 Decimal places