don't apply patch optimization when it's incorrect

Author: Kostya

jsonpatch.py

@@ -171,6 +171,10 @@ def make_patch(src, dst):
     >>> new == dst
     True
     """
+    patch = JsonPatch.from_diff(src, dst)
+    new = patch.apply(src)
+    if new != dst:
+        return JsonPatch.from_diff(src, dst, False)
     return JsonPatch.from_diff(src, dst)
 
 
@@ -268,7 +272,7 @@ def from_string(cls, patch_str):
         return cls(patch)
 
     @classmethod
-    def from_diff(cls, src, dst):
+    def from_diff(cls, src, dst, optimization=True):
         """Creates JsonPatch instance based on comparing of two document
         objects. Json patch would be created for `src` argument against `dst`
         one.
@@ -320,7 +324,7 @@ def compare_dicts(path, src, dst):
                            'value': dst[key]}
 
         def compare_lists(path, src, dst):
-            return _compare_lists(path, src, dst)
+            return _compare_lists(path, src, dst, optimization=optimization)
 
         return cls(list(compare_values([], src, dst)))
 
@@ -561,9 +565,12 @@ def apply(self, obj):
         return obj
 
 
-def _compare_lists(path, src, dst):
+def _compare_lists(path, src, dst, optimization=True):
     """Compares two lists objects and return JSON patch about."""
-    return _optimize(_compare(path, src, dst, *_split_by_common_seq(src, dst)))
+    patch = list(_compare(path, src, dst, *_split_by_common_seq(src, dst)))
+    if optimization:
+        return list(_optimize(patch))
+    return patch
 
 
 def _longest_common_subseq(src, dst):

tests.py

@@ -267,7 +267,6 @@ def test_str(self):
         self.assertEqual(json.dumps(patch_obj), patch.to_string())
 
 
-
 class MakePatchTestCase(unittest.TestCase):
 
     def test_apply_patch_to_copy(self):
@@ -336,7 +335,6 @@ def test_should_just_add_new_item_not_rebuild_all_list(self):
         res = jsonpatch.apply_patch(src, patch)
         self.assertEqual(res, dst)
 
-
     def test_escape(self):
         src = {"x/y": 1}
         dst = {"x/y": 2}
@@ -368,6 +366,17 @@ def test_issue40(self):
         dest = [7, 2, 1, 0, 9, 4, 3, 6, 5, 8]
         patch = jsonpatch.make_patch(src, dest)
 
+    def test_json_patch(self):
+        old = {
+            'queue': {'teams_out': [{'id': 3, 'reason': 'If tied'}, {'id': 5, 'reason': 'If tied'}]},
+        }
+        new = {
+            'queue': {'teams_out': [{'id': 5, 'reason': 'If lose'}]}
+        }
+        patch = jsonpatch.make_patch(old, new)
+        new_from_patch = jsonpatch.apply_patch(old, patch)
+        self.assertEqual(new, new_from_patch)
+
 
 class OptimizationTests(unittest.TestCase):
     def test_use_replace_instead_of_remove_add(self):