Add Appropriate test for loading error

freqtrade/resolvers/strategy_resolver.py

@@ -227,7 +227,16 @@ class StrategyResolver(IResolver):
                 if type(strategy).populate_exit_trend == IStrategy.populate_exit_trend:
                     raise OperationalException("`populate_exit_trend` must be implemented.")
             else:
-                # TODO: Verify if populate_buy and populate_sell are implemented
+
+                if (type(strategy).populate_buy_trend == IStrategy.populate_buy_trend
+                        and type(strategy).populate_entry_trend == IStrategy.populate_entry_trend):
+                    raise OperationalException(
+                        "`populate_entry_trend` or `populate_buy_trend` must be implemented.")
+                if (type(strategy).populate_sell_trend == IStrategy.populate_sell_trend
+                        and type(strategy).populate_exit_trend == IStrategy.populate_exit_trend):
+                    raise OperationalException(
+                        "`populate_exit_trend` or `populate_sell_trend` must be implemented.")
+
                 strategy._populate_fun_len = len(getfullargspec(strategy.populate_indicators).args)
                 strategy._buy_fun_len = len(getfullargspec(strategy.populate_buy_trend).args)
                 strategy._sell_fun_len = len(getfullargspec(strategy.populate_sell_trend).args)

tests/strategy/test_strategy_loading.py

@@ -144,6 +144,16 @@ def test_strategy_can_short(caplog, default_conf):
     assert isinstance(strat, IStrategy)
 
 
+def test_strategy_implements_populate_entry(caplog, default_conf):
+    caplog.set_level(logging.INFO)
+    default_conf.update({
+        'strategy': "StrategyTestV2",
+    })
+    default_conf['trading_mode'] = 'futures'
+    with pytest.raises(OperationalException, match="`populate_entry_trend` must be implemented."):
+        StrategyResolver.load_strategy(default_conf)
+
+
 def test_strategy_override_minimal_roi(caplog, default_conf):
     caplog.set_level(logging.INFO)
     default_conf.update({