use pytest

freqtrade/main.py

@@ -91,7 +91,8 @@ def execute_sell(trade: Trade, current_rate: float) -> None:
     whitelist = _CONF[trade.exchange.name.lower()]['pair_whitelist']
 
     profit = trade.exec_sell_order(current_rate, balance)
-    whitelist.append(trade.pair)
+    if trade.pair not in whitelist:
+        whitelist.append(trade.pair)
     message = '*{}:* Selling [{}]({}) at rate `{:f} (profit: {}%)`'.format(
         trade.exchange.name,
         trade.pair.replace('_', '/'),

setup.py

@@ -12,8 +12,8 @@ setup(name='freqtrade',
       license='GPLv3',
       packages=['freqtrade'],
       scripts=['bin/freqtrade'],
-      test_suite='nose.collector',
-      tests_require=['nose'],
+      setup_requires=['pytest-runner'],
+      tests_require=['pytest'],
       install_requires=[
           'python-bittrex==0.1.3',
           'SQLAlchemy==1.1.13',