Add helpers to merge dictionaries and get keys deep inside a dictionary

src/tests/test_helpers.py

@@ -0,0 +1,30 @@
+from utils import helpers
+
+def test_get_from_null_dict():
+    # null handling
+    assert helpers.get_from_dict(dict()) == dict()
+    assert helpers.get_from_dict(dict(), None) == None
+
+    # key present in nested dictionary
+    # 1-level dictionary
+    assert helpers.get_from_dict({'a': 1, 'b': 2}, 'a') == 1
+    assert helpers.get_from_dict({'a': 1, 'b': 2}, 'c') == None
+
+    # 2-level dictionary
+    assert helpers.get_from_dict({'a': {'a_a': 1}, 'b': 2}, 'a') == {'a_a': 1}
+    assert helpers.get_from_dict({'a': {'a_a': 1}, 'b': 2}, 'a', 'a_a') == 1
+
+    # key not present in nested dictionary
+    # 2-level_dictionary
+    assert helpers.get_from_dict({'a': {'a_a': 1}, 'b': 2}, 'b', 'b_a') == None
+
+
+def test_merge_dicts():
+    # basic merge of dicts with non-overlapping keys
+    assert helpers.merge_dicts(priority_dict={'a': 1}, default_dict={'b': 2}) == {'a': 1, 'b': 2}
+
+    # use default dict items when not present in priority dict
+    assert helpers.merge_dicts(priority_dict={}, default_dict={'b': 2}) == {'b': 2}
+
+    # do not override existing key in priority_dict with default dict
+    assert helpers.merge_dicts(priority_dict={'a': 1}, default_dict={'a': 2}) == {'a': 1}

src/utils/helpers.py

@@ -7,3 +7,22 @@ def is_none_or_empty(item):
 
 def get_absolute_path(filepath):
     return str(pathlib.Path(filepath).expanduser().absolute())
+
+
+def get_from_dict(dictionary, *args):
+    '''null-aware get from a nested dictionary
+       Returns: dictionary[args[0]][args[1]]... or None if any keys missing'''
+    current = dictionary
+    for arg in args:
+        if not hasattr(current, '__iter__') or not arg in current:
+            return None
+        current = current[arg]
+    return current
+
+
+def merge_dicts(priority_dict, default_dict):
+    merged_dict = priority_dict.copy()
+    for k, v in default_dict.items():
+        if k not in priority_dict:
+            merged_dict[k] = default_dict[k]
+    return merged_dict