Update deep_merge_dicts to disallow null-overrides

freqtrade/misc.py

@@ -129,7 +129,7 @@ def format_ms_time(date: int) -> str:
     return datetime.fromtimestamp(date/1000.0).strftime('%Y-%m-%dT%H:%M:%S')
 
 
-def deep_merge_dicts(source, destination):
+def deep_merge_dicts(source, destination, allow_null_overrides: bool = True):
     """
     Values from Source override destination, destination is returned (and modified!!)
     Sample:
@@ -142,8 +142,8 @@ def deep_merge_dicts(source, destination):
         if isinstance(value, dict):
             # get node or create one
             node = destination.setdefault(key, {})
-            deep_merge_dicts(value, node)
-        else:
+            deep_merge_dicts(value, node, allow_null_overrides)
+        elif value is not None or allow_null_overrides:
             destination[key] = value
 
     return destination

tests/test_misc.py

@@ -1,15 +1,16 @@
 # pragma pylint: disable=missing-docstring,C0103
 
 import datetime
+from copy import deepcopy
 from pathlib import Path
 from unittest.mock import MagicMock
 
 import pytest
 
-from freqtrade.misc import (decimals_per_coin, file_dump_json, file_load_json, format_ms_time,
-                            pair_to_filename, parse_db_uri_for_logging, plural, render_template,
-                            render_template_with_fallback, round_coin_value, safe_value_fallback,
-                            safe_value_fallback2, shorten_date)
+from freqtrade.misc import (decimals_per_coin, deep_merge_dicts, file_dump_json, file_load_json,
+                            format_ms_time, pair_to_filename, parse_db_uri_for_logging, plural,
+                            render_template, render_template_with_fallback, round_coin_value,
+                            safe_value_fallback, safe_value_fallback2, shorten_date)
 
 
 def test_decimals_per_coin():
@@ -203,3 +204,16 @@ def test_render_template_fallback(mocker):
 def test_parse_db_uri_for_logging(conn_url, expected) -> None:
 
     assert parse_db_uri_for_logging(conn_url) == expected
+
+
+def test_deep_merge_dicts():
+    a = {'first': {'rows': {'pass': 'dog', 'number': '1', 'test': None}}}
+    b = {'first': {'rows': {'fail': 'cat', 'number': '5', 'test': 'asdf'}}}
+    res = {'first': {'rows': {'pass': 'dog', 'fail': 'cat', 'number': '5', 'test': 'asdf'}}}
+    res2 = {'first': {'rows': {'pass': 'dog', 'fail': 'cat', 'number': '1', 'test': None}}}
+    assert deep_merge_dicts(b, deepcopy(a)) == res
+
+    assert deep_merge_dicts(a, deepcopy(b)) == res2
+
+    res2['first']['rows']['test'] = 'asdf'
+    assert deep_merge_dicts(a, deepcopy(b), allow_null_overrides=False) == res2