Add merge dict and white tests

o3skim/test/test_utils.py

+import unittest
+
+from o3skim import utils
+
+
+dict_1 = {'a': 1, 'c': 0, 'z': {'a': 1, 'c': 0}}
+dict_2 = {'b': 2, 'c': 3, 'z': {'b': 2, 'c': 3}}
+
+
+class Tests_mergedict(unittest.TestCase):
+
+    def test_merge_d1d2(self):
+        dict_3 = dict_1.copy()
+        utils.mergedicts(dict_3, dict_2)
+        self.assertEqual(dict_2, {'b': 2, 'c': 3, 'z': {'b': 2, 'c': 3}})
+        self.assertEqual(dict_3['a'], 1)
+        self.assertEqual(dict_3['b'], 2)
+        self.assertEqual(dict_3['c'], 3)
+        self.assertEqual(dict_3['z'], {'a': 1, 'b': 2, 'c': 3})
+
+    def test_merge_d2d1(self):
+        dict_3 = dict_2.copy()
+        utils.mergedicts(dict_3, dict_1) 
+        self.assertEqual(dict_1, {'a': 1, 'c': 0, 'z': {'a': 1, 'c': 0}})
+        self.assertEqual(dict_3['a'], 1)
+        self.assertEqual(dict_3['b'], 2)
+        self.assertEqual(dict_3['c'], 0)
+        self.assertEqual(dict_3['z'], {'a': 1, 'b': 2, 'c': 0})

o3skim/utils.py

@@ -88,3 +88,20 @@ def save(file_name, metadata):
     """
     with open(file_name, 'w+') as ymlfile:
         yaml.dump(metadata, ymlfile, allow_unicode=True)
+
+
+def mergedicts(d1, d2):
+    """Merges dict d2 in dict d2 recursively. If two keys exist in 
+    both dicts, the value in d1 is superseded by the value in d2.
+
+    :param d1: Dict to be recursively completed by d2.
+    :type d1: dict
+
+    :param d2: Dict to be recursively merged in d1.
+    :type d2: dict
+    """
+    for key in d2:
+        if key in d1 and isinstance(d1[key], dict) and isinstance(d2[key], dict):
+            mergedicts(d1[key], d2[key])
+        else:
+            d1[key] = d2[key]