Always rollback to the target revision

This PS removes some additional validations around not being
able to rollback to a target revision:
  - if the target revision == current revision
  - if the target revision is effectively equivalent to the current
    revision (in terms of constituent documents)

Change-Id: I92f8f9557f96b6a27f0dcef4f3138d542e5aa915

deckhand/db/sqlalchemy/api.py

@@ -1021,10 +1021,9 @@ def revision_rollback(revision_id, latest_revision, session=None):
         (d['data_hash'], d['metadata_hash'])
         for d in latest_revision['documents']]
 
-    # If the rollback revision is the same as the latest revision, then there's
-    # no point in rolling back.
     if latest_revision['id'] == revision_id:
-        raise errors.InvalidRollback(revision_id=revision_id)
+        LOG.debug('The revision being rolled back to is the current revision.'
+                  'Expect no meaningful changes.')
 
     orig_revision = revision_get(revision_id, session=session)
 
@@ -1039,10 +1038,12 @@ def revision_rollback(revision_id, latest_revision, session=None):
         else:
             doc_diff[orig_doc['id']] = False
 
-    # If no changes have been made between the target revision to rollback to
-    # and the latest revision, raise an exception.
+    # No changes have been made between the target revision to rollback to
+    # and the latest revision.
     if set(doc_diff.values()) == set([False]):
-        raise errors.InvalidRollback(revision_id=revision_id)
+        LOG.debug('The revision being rolled back to has the same documents '
+                  'as that of the current revision. Expect no meaningful '
+                  'changes.')
 
     # Create the new revision,
     new_revision = models.Revision()

deckhand/errors.py

@@ -263,12 +263,6 @@ class RevisionTagBadFormat(DeckhandException):
     code = 400
 
 
-class InvalidRollback(DeckhandException):
-    msg_fmt = ("The requested rollback for target revision %(revision)s is "
-               "invalid as the latest revision matches the target revision.")
-    code = 400
-
-
 class BarbicanException(DeckhandException):
 
     def __init__(self, message, code):

deckhand/tests/unit/base.py

@@ -45,6 +45,31 @@ class DeckhandTestCase(testtools.TestCase):
         elif isinstance(collection, dict):
             self.assertEqual(0, len(collection.keys()))
 
+    def assertDictItemsAlmostEqual(self, first, second, ignore):
+        """Assert that the items in a dictionary or list of dictionaries
+        are equal, except for the keys specified in ``ignore``.
+
+        Both first and second must contain the keys specified in ``ignore``.
+
+        :param first: First dictionary or list of dictionaries to compare.
+        :type first: dict or list[dict]
+        :param second: Second dictionary or list of dictionaries to compare.
+        :type second: dict or list[dict]
+        :param ignore: List of keys to ignore in both dictionaries or list
+            of dictionaries.
+        :type ignore: list or tuple
+        """
+        if not isinstance(first, list):
+            first = [first]
+        if not isinstance(second, list):
+            second = [second]
+        for key in ignore:
+            for item in first:
+                item.pop(key)
+            for item in second:
+                item.pop(key)
+        self.assertEqual(first, second)
+
     def patch(self, target, autospec=True, **kwargs):
         """Returns a started `mock.patch` object for the supplied target.
 

deckhand/tests/unit/db/test_revision_rollback.py

@@ -83,3 +83,18 @@ class TestRevisionRollback(base.TestDbBase):
                          [d['revision_id'] for d in rollback_documents])
         self.assertEqual([1, 1, 4, 4],
                          [d['orig_revision_id'] for d in rollback_documents])
+
+    def test_rollback_to_revision_same_as_current_revision(self):
+        payload = base.DocumentFixture.get_minimal_multi_fixture(count=4)
+        bucket_name = test_utils.rand_name('bucket')
+        created_documents = self.create_documents(bucket_name, payload)
+        orig_revision_id = created_documents[0]['revision_id']
+        orig_documents = self.list_revision_documents(orig_revision_id)
+
+        rollback_revision = self.rollback_revision(orig_revision_id)
+        self.assertDictItemsAlmostEqual(
+            sorted(orig_documents, key=lambda d: d['created_at']),
+            sorted(rollback_revision['documents'],
+                   key=lambda d: d['created_at']),
+            ignore=['created_at', 'updated_at', 'revision_id',
+                    'orig_revision_id', 'id'])

deckhand/tests/unit/db/test_revision_rollback_negative.py

@@ -1,47 +0,0 @@
-# Copyright 2017 AT&T Intellectual Property.  All other rights reserved.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-from deckhand import errors
-from deckhand.tests import test_utils
-from deckhand.tests.unit.db import base
-
-
-class TestRevisionRollbackNegative(base.TestDbBase):
-
-    def test_rollback_same_revision_raises_error(self):
-        # Revision 1: Create 4 documents.
-        payload = base.DocumentFixture.get_minimal_multi_fixture(count=4)
-        bucket_name = test_utils.rand_name('bucket')
-        created_documents = self.create_documents(bucket_name, payload)
-        orig_revision_id = created_documents[0]['revision_id']
-
-        # Attempt to rollback to the latest revision, which should result
-        # in an error.
-        self.assertRaises(
-            errors.InvalidRollback, self.rollback_revision, orig_revision_id)
-
-    def test_rollback_unchanged_revision_history_raises_error(self):
-        # Revision 1: Create 4 documents.
-        payload = base.DocumentFixture.get_minimal_multi_fixture(count=4)
-        bucket_name = test_utils.rand_name('bucket')
-        created_documents = self.create_documents(bucket_name, payload)
-        orig_revision_id = created_documents[0]['revision_id']
-
-        # Create a 2nd revision that is a carbon-copy of 1st.
-        self.create_documents(bucket_name, payload)
-
-        # Attempt to rollback to the 1st revision, which should result in an
-        # error, as it is identical to the latest revision.
-        self.assertRaises(
-            errors.InvalidRollback, self.rollback_revision, orig_revision_id)