From a48412427218109f937b17bf2309d6cd70cd79bc Mon Sep 17 00:00:00 2001
From: hroff-1902 <hroff_raeyd9tzpttf@mail.ru>
Date: Mon, 25 May 2020 23:14:51 +0300
Subject: [PATCH] Raise exception if StaticPairList on a non-first position

---
 freqtrade/pairlist/StaticPairList.py |  7 ++++++-
 tests/pairlist/test_pairlist.py      | 19 ++++++++++++++-----
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/freqtrade/pairlist/StaticPairList.py b/freqtrade/pairlist/StaticPairList.py
index 0218833e3..4c260d2fe 100644
--- a/freqtrade/pairlist/StaticPairList.py
+++ b/freqtrade/pairlist/StaticPairList.py
@@ -6,6 +6,7 @@ Provides pair white list as it configured in config
 import logging
 from typing import Dict, List
 
+from freqtrade.exceptions import OperationalException
 from freqtrade.pairlist.IPairList import IPairList
 
 
@@ -47,4 +48,8 @@ class StaticPairList(IPairList):
         :param tickers: Tickers (from exchange.get_tickers()). May be cached.
         :return: new whitelist
         """
-        return pairlist
+        if self._pairlist_pos != 0:
+            raise OperationalException(f"{self.name} can only be used in the first position "
+                                       "in the list of Pairlist Handlers.")
+        else:
+            return pairlist
diff --git a/tests/pairlist/test_pairlist.py b/tests/pairlist/test_pairlist.py
index 3e3241071..9c35eae1b 100644
--- a/tests/pairlist/test_pairlist.py
+++ b/tests/pairlist/test_pairlist.py
@@ -279,28 +279,32 @@ def test_VolumePairList_refresh_empty(mocker, markets_empty, whitelist_conf):
      "BTC", ['ETH/BTC', 'TKN/BTC']),
     # PrecisionFilter only
     ([{"method": "PrecisionFilter"}],
-     "BTC", None),  # OperationalException expected
+     "BTC", 'filter_at_the_beginning'),  # OperationalException expected
     # PriceFilter after StaticPairList
     ([{"method": "StaticPairList"},
       {"method": "PriceFilter", "low_price_ratio": 0.02}],
      "BTC", ['ETH/BTC', 'TKN/BTC']),
     # PriceFilter only
     ([{"method": "PriceFilter", "low_price_ratio": 0.02}],
-     "BTC", None),  # OperationalException expected
+     "BTC", 'filter_at_the_beginning'),  # OperationalException expected
     # ShuffleFilter after StaticPairList
     ([{"method": "StaticPairList"},
       {"method": "ShuffleFilter", "seed": 42}],
      "BTC", ['TKN/BTC', 'ETH/BTC', 'HOT/BTC']),
     # ShuffleFilter only
     ([{"method": "ShuffleFilter", "seed": 42}],
-     "BTC", None),  # OperationalException expected
+     "BTC", 'filter_at_the_beginning'),  # OperationalException expected
     # SpreadFilter after StaticPairList
     ([{"method": "StaticPairList"},
       {"method": "SpreadFilter", "max_spread_ratio": 0.005}],
      "BTC", ['ETH/BTC', 'TKN/BTC']),
     # SpreadFilter only
     ([{"method": "SpreadFilter", "max_spread_ratio": 0.005}],
-     "BTC", None),  # OperationalException expected
+     "BTC", 'filter_at_the_beginning'),  # OperationalException expected
+    # Static Pairlist after VolumePairList, on a non-first position
+    ([{"method": "VolumePairList", "number_assets": 5, "sort_key": "bidVolume"},
+      {"method": "StaticPairList"}],
+     "BTC", 'static_in_the_middle'),
 ])
 def test_VolumePairList_whitelist_gen(mocker, whitelist_conf, shitcoinmarkets, tickers,
                                       pairlists, base_currency, whitelist_result,
@@ -317,11 +321,16 @@ def test_VolumePairList_whitelist_gen(mocker, whitelist_conf, shitcoinmarkets, t
                           )
 
     # Set whitelist_result to None if pairlist is invalid and should produce exception
-    if whitelist_result is None:
+    if whitelist_result == 'filter_at_the_beginning':
         with pytest.raises(OperationalException,
                            match=r"This Pairlist Handler should not be used at the first position "
                                  r"in the list of Pairlist Handlers."):
             freqtrade.pairlists.refresh_pairlist()
+    elif whitelist_result == 'static_in_the_middle':
+        with pytest.raises(OperationalException,
+                           match=r"StaticPairList can only be used in the first position "
+                                 r"in the list of Pairlist Handlers."):
+            freqtrade.pairlists.refresh_pairlist()
     else:
         freqtrade.pairlists.refresh_pairlist()
         whitelist = freqtrade.pairlists.whitelist