Add initial test for custom_data

tests/persistence/test_trade_custom_data.py

@@ -0,0 +1,34 @@
+import pytest
+from sqlalchemy import select
+
+from freqtrade.persistence import Trade
+from tests.conftest import create_mock_trades_usdt
+
+
+@pytest.mark.usefixtures("init_persistence")
+def test_trade_custom_data(fee):
+    create_mock_trades_usdt(fee)
+
+    trade1 = Trade.session.scalars(select(Trade)).first()
+
+    assert trade1.get_all_custom_data() == []
+    trade1.set_custom_data('test_str', 'test_value')
+    trade1.set_custom_data('test_int', 1)
+    trade1.set_custom_data('test_float', 1.55)
+    trade1.set_custom_data('test_bool', True)
+    trade1.set_custom_data('test_dict', {'test': 'dict'})
+
+    assert trade1.get_custom_data('test_str') == 'test_value'
+
+    assert trade1.get_custom_data('test_int') == 1
+    assert isinstance(trade1.get_custom_data('test_int'), int)
+
+    assert trade1.get_custom_data('test_float') == 1.55
+    assert isinstance(trade1.get_custom_data('test_float'), float)
+
+    assert trade1.get_custom_data('test_bool') is True
+    assert isinstance(trade1.get_custom_data('test_bool'), bool)
+
+    assert trade1.get_custom_data('test_dict') == {'test': 'dict'}
+    assert isinstance(trade1.get_custom_data('test_dict'), dict)
+    assert len(trade1.get_all_custom_data()) == 5