Tested setting categories with dict.

src/datreant/core/limbs.py

@@ -441,6 +441,18 @@ def __delitem__(self, category):
         """
         self.remove(category)
 
+    def __eq__(self, other):
+        if isinstance(other, (Categories, dict)):
+            return dict(self) == dict(other)
+        else:
+            raise TypeError("Operands must be categories or dicts.")
+
+    def __req__(self, other):
+        if isinstance(other, (Categories, dict)):
+            return dict(self) == dict(other)
+        else:
+            raise TypeError("Operands must be categories or dicts.")
+
     def __iter__(self):
         return self._dict().__iter__()
 

src/datreant/core/tests/test_treants.py

@@ -344,6 +344,29 @@ def test_get_categories(self, treant):
             assert treant.categories[{'leaves', 'bark'}] == {'leaves': 'many',
                                                              'bark': 'dark'}
 
+        def test_set_categories(self, treant, tmpdir):
+            a_dict = {'leaves': 'many', 'bark': 'dark'}
+
+            treant.categories = a_dict
+            assert treant.categories == a_dict
+
+            a_dict.update({'roots': 'shallow'})
+
+            assert treant.categories != a_dict
+            treant.categories = a_dict
+            assert a_dict == treant.categories
+
+            # test setting from other Treant's categories
+            with tmpdir.as_cwd():
+                s = dtr.Treant('sprout')
+
+            s.categories = {'shoes': False, 'shirt': False}
+
+            assert treant.categories != s.categories
+
+            treant.categories = s.categories
+            assert treant.categories == s.categories
+
 
 class TestGroup(TestTreant):
     """Test Group-specific features.