Improve some test coverage

freqtrade/plugins/pairlist/RemotePairList.py

@@ -65,7 +65,7 @@ class RemotePairList(IPairList):
 
         if self._pairlist_pos == 0 and self._mode == 'blacklist':
             raise OperationalException(
-                'At `blacklist` mode RemotePairList can not be on the first '
+                'A `blacklist` mode RemotePairList can not be on the first '
                 'position of your pairlist.')
 
     @property
@@ -85,7 +85,7 @@ class RemotePairList(IPairList):
 
     @staticmethod
     def description() -> str:
-        return "Retrieve pairs from a remote API."
+        return "Retrieve pairs from a remote API or local file."
 
     @staticmethod
     def available_parameters() -> Dict[str, PairlistParameter]:

tests/plugins/test_remotepairlist.py

@@ -197,13 +197,28 @@ def test_remote_pairlist_init_wrong_mode(mocker, rpl_config):
         }
     ]
 
-    get_patched_exchange(mocker, rpl_config)
     with pytest.raises(
         OperationalException,
         match=r'`mode` not configured correctly. Supported Modes are "whitelist","blacklist"'
     ):
         get_patched_freqtradebot(mocker, rpl_config)
 
+    rpl_config['pairlists'] = [
+        {
+            "method": "RemotePairList",
+            "mode": "blacklist",
+            "number_assets": 20,
+            "pairlist_url": "http://example.com/pairlist",
+            "keep_pairlist_on_failure": True,
+        }
+    ]
+
+    with pytest.raises(
+            OperationalException,
+            match=r'A `blacklist` mode RemotePairList can not be.*first.*'
+    ):
+        get_patched_freqtradebot(mocker, rpl_config)
+
 
 def test_remote_pairlist_init_wrong_proc_mode(mocker, rpl_config):
     rpl_config['pairlists'] = [