Added Cobra dict-to-etree conversion and tests

This was a missing part of the Cobra implementation.
Now we can convert a dict back to etree (XML).

README.rst

@@ -195,3 +195,4 @@ Roadmap
 
 * Test cases for Unicode
 * Support for namespaces and namespace prefixes
+* Support XML comments

tests/test_xmljson.py

@@ -602,10 +602,51 @@ def test_data(self):
 
 
 class TestCobra(TestXmlJson):
-    @unittest.skip('To be written')
+
     def test_etree(self, converter=None):
         'Cobra conversion from data to etree'
-        pass
+        eq = self.check_etree(xmljson.cobra)
+
+        eq({'animal': {'attributes': {}}}, '<animal/>')
+        eq({'animal': {'attributes': {}, 'children': ['Deka']}}, '<animal>Deka</animal>')
+        eq({'animal': {'attributes': {}, 'children': [1]}}, '<animal>1</animal>')
+        eq({'animal': {'attributes': {'name': 1}}}, '<animal name="1"/>')
+        eq({'animal': 'is my cat'},
+           '<animal>is my cat</animal>')
+        eq({'animal': {'attributes': {}, 'children': [{'dog': 'Charlie'}, {'cat': 'Deka'}]}},
+           '<animal><dog>Charlie</dog><cat>Deka</cat></animal>')
+        eq({'animal': {'attributes': {}, 'children': [{'dog': 'Charlie'}, {'dog': 'Mad Max'}]}},
+           '<animal><dog>Charlie</dog><dog>Mad Max</dog></animal>')
+        #eq({'animal': {'attributes': {}, 'children': [{'dog': {'attributes': {}, 'children': ['Charlie', 'Mad Max']}}]}},
+        #   '<animal><dog>Charlie</dog><dog>Mad Max</dog></animal>')
+        eq({'animal': {'attributes': {'dog': 'Charlie', 'cat': 'Deka'}}},
+           '<animal dog="Charlie" cat="Deka"/>')
+        eq({'animal': {'attributes': {}, 'children': [' in my house ', {'dog': 'Charlie'}]}},
+           '<animal> in my house <dog>Charlie</dog></animal>')
+        eq({'animal': {'attributes': {'dog': 'Charlie'}, 'children': [' in my house ']}},
+           '<animal dog="Charlie"> in my house </animal>')
+
+        # Test edge cases
+        eq('x', '<x/>')             # Strings become elements
+        eq({})                      # Empty objects become empty nodes
+        eq(Dict([                   # Multiple keys become multiple nodes
+            ('x', 'a'),
+            ('y', 'b')
+        ]), '<x>a</x>', '<y>b</y>')
+        with self.assertRaises(Exception):
+            eq({'x': {'@x': 1}}, '<x x="1"/>')
+
+        # Nested elements
+        eq({'alice': {'attributes': {}, 'children': [
+            {'bob': {'attributes': {}, 'children': [{'charlie': {'attributes': {}}}]}},
+            {'david': {'attributes': {}, 'children': [{'edgar': {'attributes': {}}}]}}]}},
+           '<alice><bob><charlie/></bob><david><edgar/></david></alice>')
+
+        # Multiple elements at the same level become array elements.
+        eq({'alice': {'attributes': {}, 'children': [
+            {'bob': {'attributes': {}, 'children': [{'charlie': {'attributes': {}}}]}},
+            {'bob': {'attributes': {}, 'children': [{'david': {'attributes': {}}}]}}]}},
+           '<alice><bob><charlie/></bob><bob><david/></bob></alice>')
 
     @unittest.skip('To be written')
     def test_html(self):

xmljson/__init__.py

@@ -252,6 +252,35 @@ class Cobra(XMLData):
     def __init__(self, **kwargs):
         super(Cobra, self).__init__(simple_text=True, text_content=True,
                                     xml_fromstring=False, **kwargs)
+    def etree(self, data, root=None):
+        '''Convert data structure into a list of etree.Element'''
+        result = self.list() if root is None else root
+        if isinstance(data, (self.dict, dict)):
+            for key, value in data.items():
+                if isinstance(value, (self.dict, dict)):
+                    elem = self.element(key)
+                    result.append(elem)
+
+                    if 'attributes' in value:
+                        for k, v in value['attributes'].items():
+                            elem.set(k, self._tostring(v))
+                    else:
+                        raise ValueError("Cobra convention requires an attributes key for each element")
+
+                    if 'children' in value:
+                        for v in value['children']:
+                            self.etree(v, root=elem)
+                else:
+                    elem = self.element(key)
+                    elem.text = self._tostring(value)
+                    result.append(elem)
+        else:
+            if root is not None:
+                root.text = self._tostring(data)
+            else:
+                result.append(self.element(self._tostring(data)))
+
+        return result
 
     def data(self, root):
         '''Convert etree.Element into a dictionary'''