Add get_open_trade_count() to simplify getting open trade count.

tests/test_freqtradebot.py

@@ -473,8 +473,6 @@ def test_create_trade_no_signal(default_conf_usdt, fee, mocker) -> None:
     freqtrade = FreqtradeBot(default_conf_usdt)
     patch_get_signal(freqtrade, enter_long=False, exit_long=False)
 
-    Trade.query = MagicMock()
-    Trade.query.filter = MagicMock()
     assert not freqtrade.create_trade('ETH/USDT')
 
 

tests/test_persistence.py

@@ -1689,6 +1689,7 @@ def test_get_open(fee, is_short, use_db):
 
     create_mock_trades(fee, is_short, use_db)
     assert len(Trade.get_open_trades()) == 4
+    assert Trade.get_open_trade_count() == 4
 
     Trade.use_db = True
 
@@ -1701,6 +1702,7 @@ def test_get_open_lev(fee, use_db):
 
     create_mock_trades_with_leverage(fee, use_db)
     assert len(Trade.get_open_trades()) == 5
+    assert Trade.get_open_trade_count() == 5
 
     Trade.use_db = True