fix tag deletion

moto/ec2/responses/tags.py

@@ -15,7 +15,8 @@ class TagResponse(object):
         return CREATE_RESPONSE
 
     def delete_tags(self):
-        ec2_backend.delete_tag()
+        for resource_id, tag in self.resource_ids.iteritems():
+            ec2_backend.delete_tag(resource_id, tag[0])
         template = Template(DELETE_RESPONSE)
         return template.render(reservations=ec2_backend.all_reservations())
 

moto/ec2/utils.py

@@ -48,7 +48,12 @@ def resource_ids_from_querystring(querystring_dict):
         if prefix in key:
             resource_index = key.replace(prefix + ".", "")
             tag_key = querystring_dict.get("Tag.{}.Key".format(resource_index))[0]
-            tag_value = querystring_dict.get("Tag.{}.Value".format(resource_index))[0]
+
+            tag_value_key = "Tag.{}.Value".format(resource_index)
+            if tag_value_key in querystring_dict:
+                tag_value = querystring_dict.get(tag_value_key)[0]
+            else:
+                tag_value = None
             response_values[value[0]] = (tag_key, tag_value)
 
     return response_values

tests/test_ec2/test_tags.py

@@ -16,3 +16,6 @@ def test_instance_launch_and_terminate():
     tag = tags[0]
     tag.name.should.equal("a key")
     tag.value.should.equal("some value")
+
+    instance.remove_tag("a key")
+    conn.get_all_tags().should.have.length_of(0)