Merge pull request #6 from jedipi/feature/overwriting-yaml-with-missi…

…ng-subsections

support layering a yaml file over another without having all sections

layeredconfig/yamlfile.py

@@ -27,6 +27,8 @@ def __init__(self, yamlfilename=None, writable=True, **kwargs):
             yamlfilename = kwargs['parent'].yamlfilename
         if 'defaults' in kwargs:
             self.source = kwargs['defaults']
+        elif kwargs.get('empty', False):
+            self.source = {}
         else:
             with codecs.open(yamlfilename, encoding="utf-8") as fp:
                 # do we need safe_load?

tests/test_layeredconfig.py

@@ -585,6 +585,37 @@ def test_write(self):
             got = fp.read().replace("\r\n", "\n")
         self.assertEqual(want, got)
 
+
+class YamlOverwritingTestCase(unittest.TestCase):
+    def tearDown(self):
+        os.unlink('source1.yaml')
+        os.unlink('source2.yaml')
+
+    def test_overwriting_yaml_with_missing_subsections(self):
+        with open('source1.yaml', 'w') as fp:
+            fp.write("""
+section:
+  key1: key1_value1
+  subsection:
+    subsection_key1: subsection_key1_value1
+        """)
+
+        with open('source2.yaml', 'w') as fp:
+            fp.write("""
+section:
+  key1: key1_value2
+        """)
+        config = LayeredConfig(
+            YAMLFile('source1.yaml'),
+            YAMLFile('source2.yaml')
+        )
+        self.assertEquals(config.section.key1, 'key1_value2')
+        self.assertEquals(
+            config.section.subsection.subsection_key1,
+            'subsection_key1_value1'
+        )
+
+
 class TestPListFile(unittest.TestCase, TestConfigSourceHelper):
 
     supported_types = (str, int, bool, list, datetime)