A new method named modify needs to be a selective operation

Issues:
Fixes #609

Problem:
Instead of puting the whole configuration object in a request to the
server, modify will only submit the explicitly specified parameters in
its kwargs, in a patch request to the server. This feature should be
implemented after #608.

Analysis:
Added modify in ResourceBase, and created a couple of non-public helper
functions to make common usage among _update and _modify.

Tests:
Unit tests pass, but functionals still need to be written. Only one
functional test exists currently.

Author: Paul Breaux

f5/bigip/resource.py

@@ -444,9 +444,17 @@ def _modify(self, **kwargs):
         requests_params, patch_uri, session, read_only = \
             self._prepare_put_or_patch(kwargs)
         self._check_for_boolean_pair_reduction(kwargs)
-        data_dict = self._pop_read_only_attrs(kwargs, read_only)
-        data_dict.update(kwargs)
-        response = session.patch(patch_uri, json=data_dict, **requests_params)
+
+        read_only_mutations = []
+        for attr in read_only:
+            if attr in kwargs:
+                read_only_mutations.append(attr)
+        if read_only_mutations:
+            msg = 'Attempted to mutate read-only attribute(s): %s' \
+                % read_only_mutations
+            raise AttemptedMutationOfReadOnly(msg)
+
+        response = session.patch(patch_uri, json=kwargs, **requests_params)
         self._local_update(response.json())
 
     def modify(self, **kwargs):
@@ -473,13 +481,6 @@ def _prepare_put_or_patch(self, kwargs):
         read_only = self._meta_data.get('read_only_attributes', [])
         return requests_params, update_uri, session, read_only
 
-    def _pop_read_only_attrs(self, kwargs, read_only):
-        """Remove any read-only attributes from kwargs"""
-
-        for attr in read_only:
-            kwargs.pop(attr, '')
-        return kwargs
-
     def _update(self, **kwargs):
         """wrapped with update, override that in a subclass to customize"""
 
@@ -512,7 +513,8 @@ def _update(self, **kwargs):
         # the data dict with the attributes.  If they pass in read-only attrs
         # in the method call we are going to let BIG-IP® let them know about it
         # when it fails
-        data_dict = self._pop_read_only_attrs(data_dict, read_only)
+        for attr in read_only:
+            data_dict.pop(attr, '')
 
         data_dict.update(kwargs)
 

f5/bigip/test/test_resource.py

@@ -16,9 +16,9 @@
 import pytest
 import requests
 
+from f5.bigip.resource import AttemptedMutationOfReadOnly
 from f5.bigip.resource import BooleansToReduceHaveSameValue
 from f5.bigip.resource import Collection
-from f5.bigip.resource import AttemptedMutationOfReadOnly
 from f5.bigip.resource import DeviceProvidesIncompatibleKey
 from f5.bigip.resource import ExclusiveAttributesPresent
 from f5.bigip.resource import GenerationMismatch
@@ -346,7 +346,7 @@ def test_Collection_removal(self):
         assert 'contained' in r.__dict__
         r.modify(a=u"b")
         submitted = r._meta_data['bigip']. \
-            _meta_data['r_session'].patch.call_args[1]['json']
+            _meta_data['icr_session'].patch.call_args[1]['json']
 
         assert 'contained' not in submitted
 

test/functional/tm/ltm/test_virtual.py

@@ -18,6 +18,7 @@
 from f5.bigip.resource import MissingRequiredCreationParameter
 from f5.bigip.resource import MissingRequiredReadParameter
 
+import copy
 from pprint import pprint as pp
 import pytest
 
@@ -63,6 +64,19 @@ def test_virtual_create_refresh_update_delete_load(
         virtual2 = vc1.virtual.load(partition='Common', name='vstest1')
         assert virtual2.selfLink == virtual1.selfLink
 
+    def test_virtual_modify(self, request, mgmt_root, setup_device_snapshot):
+        virtual1, vc1 = setup_virtual_test(
+            request, mgmt_root, 'Common', 'modtest1'
+        )
+        original_dict = copy.copy(virtual1.__dict__)
+        desc = 'description'
+        virtual1.modify(description='Cool mod test')
+        for k, v in original_dict.items():
+            if k != desc:
+                original_dict[k] = virtual1.__dict__[k]
+            elif k == desc:
+                virtual1.__dict__[k] == 'Cool mod test'
+
 
 def test_profiles_CE(
         mgmt_root, opt_release, setup_device_snapshot