Add test for assert error

freqtrade/strategy/interface.py

@@ -279,11 +279,12 @@ class IStrategy(ABC):
             dataframe = self._analyze_ticker_internal(dataframe, {'pair': pair})
             self.assert_df(dataframe, df_len, df_close, df_date)
         except ValueError as error:
-            logger.warning(
-                'Unable to analyze candle (OHLCV) data for pair %s: %s',
-                pair,
-                str(error)
-            )
+            logger.warning('Unable to analyze candle (OHLCV) data for pair %s: %s',
+                           pair, str(error))
+            return False, False
+        except DependencyException as error:
+            logger.warning("Unable to analyze candle (OHLCV) data for pair %s: %s",
+                           pair, str(error))
             return False, False
         except Exception as error:
             logger.exception(

tests/strategy/test_interface.py

@@ -6,6 +6,7 @@ from unittest.mock import MagicMock
 import arrow
 from pandas import DataFrame
 
+from freqtrade.exceptions import DependencyException
 from freqtrade.configuration import TimeRange
 from freqtrade.data.history import load_data
 from freqtrade.persistence import Trade
@@ -105,6 +106,26 @@ def test_get_signal_old_dataframe(default_conf, mocker, caplog, ohlcv_history):
     assert log_has('Outdated history for pair xyz. Last tick is 16 minutes old', caplog)
 
 
+def test_assert_df_raise(default_conf, mocker, caplog, ohlcv_history):
+    # default_conf defines a 5m interval. we check interval * 2 + 5m
+    # this is necessary as the last candle is removed (partial candles) by default
+    ohlcv_history.loc[1, 'date'] = arrow.utcnow().shift(minutes=-16)
+    # Take a copy to correctly modify the call
+    mocked_history = ohlcv_history.copy()
+    mocked_history['sell'] = 0
+    mocked_history['buy'] = 0
+    mocked_history.loc[1, 'buy'] = 1
+
+    caplog.set_level(logging.INFO)
+    mocker.patch.object(
+        _STRATEGY, 'assert_df',
+        side_effect=DependencyException('Dataframe returned...')
+    )
+    assert (False, False) == _STRATEGY.get_signal('xyz', default_conf['ticker_interval'],
+                                                  ohlcv_history)
+    assert log_has('Unable to analyze candle (OHLCV) data for pair xyz: Dataframe returned...', caplog)
+
+
 def test_get_signal_handles_exceptions(mocker, default_conf):
     exchange = get_patched_exchange(mocker, default_conf)
     mocker.patch.object(