Add tests for ohlcv_get_available_data

freqtrade/data/history/jsondatahandler.py

@@ -29,9 +29,10 @@ class JsonDataHandler(IDataHandler):
         :param datadir: Directory to search for ohlcv files
         :return: List of Pair
         """
-        _tmp = [re.search(r'^([a-zA-Z_]+)\-(\S+)(?=.json)', p.name)
+        _tmp = [re.search(r'^([a-zA-Z_]+)\-(\d+\S+)(?=.json)', p.name)
                 for p in datadir.glob(f"*.{cls._get_file_extension()}")]
-        return [(match[1].replace('_', '/'), match[2]) for match in _tmp if len(match.groups()) > 1]
+        return [(match[1].replace('_', '/'), match[2]) for match in _tmp
+                if match and len(match.groups()) > 1]
 
     @classmethod
     def ohlcv_get_pairs(cls, datadir: Path, timeframe: str) -> List[str]: