run mypy also against tests

freqtrade/strategy/informative_decorator.py

@@ -23,7 +23,7 @@ class InformativeData:
 def informative(timeframe: str, asset: str = '',
                 fmt: Optional[Union[str, Callable[[Any], str]]] = None,
                 *,
-                candle_type: Optional[CandleType] = None,
+                candle_type: Optional[Union[CandleType, str]] = None,
                 ffill: bool = True) -> Callable[[PopulateIndicators], PopulateIndicators]:
     """
     A decorator for populate_indicators_Nn(self, dataframe, metadata), allowing these functions to

freqtrade/strategy/interface.py

@@ -110,7 +110,7 @@ class IStrategy(ABC, HyperStrategyMixin):
     # Class level variables (intentional) containing
     # the dataprovider (dp) (access to other candles, historic data, ...)
     # and wallets - access to the current balance.
-    dp: Optional[DataProvider]
+    dp: DataProvider
     wallets: Optional[Wallets] = None
     # Filled from configuration
     stake_currency: str