Return empty dictionary when file has no properties

Fix dsoprea#89: properties method failed when no props defined

When a file has no properties, the xml doesn't contain 'target' and
target_elem is None. To conform to the documentation for properties,
return an empty dict (instead of None).

Test for both no properties and mime type property (writing a binary
file in the simplest way I can find that works in py2 and py3).

svn/common.py

@@ -154,6 +154,9 @@ def properties(self, rel_path=None):
         # query the proper list of this path
         root = xml.etree.ElementTree.fromstring(result)
         target_elem = root.find('target')
+        if not target_elem:
+            return {}
+
         property_names = [p.attrib["name"]
                           for p in target_elem.findall('property')]
 

tests/test_common.py

@@ -14,6 +14,23 @@ def __init__(self, *args, **kwargs):
         self.maxDiff = None
         super(TestCommonClient, self).__init__(*args, **kwargs)
 
+    def test_properties(self):
+        with svn.test_support.temp_repo():
+            with svn.test_support.temp_checkout() as (working_path, lc):
+                svn.test_support.populate_bigger_file_changes1()
+
+                self.assertEqual(0, len(lc.properties('new_file')))
+                self.assertEqual(0, len(lc.properties('committed_unchanged')))
+
+                binary_file = 'binary.dat'
+                with open(os.path.join(working_path, binary_file), 'wb') as f:
+                    f.write(bytearray(range(10)))
+                lc.add(binary_file) # file must be added to have props detected
+                binary_props = lc.properties(binary_file)
+                self.assertEqual(1, len(binary_props))
+                self.assertIsNotNone(binary_props['svn:mime-type'])
+                self.assertEqual('application/octet-stream', binary_props['svn:mime-type'])
+
     def test_update(self):
         with svn.test_support.temp_repo():
             with svn.test_support.temp_checkout() as (_, lc):