update 409 Conflict to return metadata of target

 * Return metadata about the conflicting object when trying to upload
   a file with the same name as one that already exists. This metadata
   includes the update url, allowing the requestor overwrite the
   existing file without having to make additional queries to get its
   metadata.

   If the conflicting object is a folder, we do not return metadata
   about it. Overwriting a folder with a single request is not a
   supported action at this time.

 * Update tests for new behavior.

Author: felliott

tests/providers/onedrive/test_provider.py

@@ -1,4 +1,5 @@
 import io
+import json
 import pytest
 
 import aiohttpretty
@@ -701,8 +702,8 @@ async def test_upload_exists(self, provider, file_stream, readwrite_fixtures):
             file_metadata, created = await provider.upload(file_stream, path, conflict='warn')
 
         assert aiohttpretty.has_call(method='GET', uri=metadata_url)
-        assert e.value.message == ('Cannot complete action: file or folder "{}" '
-                                   'already exists in this location'.format(path.name))
+        assert json.loads(e.value.message)['message'] == ('Cannot complete action: file or folder "{}" '
+                                                          'already exists in this location'.format(path.name))
 
     @pytest.mark.aiohttpretty
     @pytest.mark.asyncio

tests/server/api/v1/test_create_mixin.py

@@ -1,3 +1,4 @@
+import json
 from http import client
 from unittest import mock
 
@@ -48,19 +49,19 @@ async def test_postvalidate_put_folder(self, http_request):
         ])
 
     @pytest.mark.asyncio
-    async def test_postvalidate_put_folder_naming_conflict(self, http_request):
+    async def test_postvalidate_put_folder_naming_conflict(self, http_request, mock_file_metadata):
 
         handler = mock_handler(http_request)
         handler.path = WaterButlerPath('/Folder1/')
         handler.kind = 'folder'
         handler.get_query_argument = mock.Mock(return_value='child!')
-        handler.provider.exists = MockCoroutine(return_value=True)
+        handler.provider.exists = MockCoroutine(return_value=mock_file_metadata)
 
         with pytest.raises(exceptions.NamingConflict) as exc:
             await handler.postvalidate_put()
 
-        assert exc.value.message == 'Cannot complete action: file or folder "child!" already ' \
-                                    'exists in this location'
+        assert json.loads(exc.value.message)['message'] == 'Cannot complete action: file or folder ' \
+                                                           '"child!" already exists in this location'
 
         assert handler.target_path == WaterButlerPath('/Folder1/child!/')
         handler.get_query_argument.assert_called_once_with('name', default=None)
@@ -85,20 +86,21 @@ async def test_postvalidate_put_cant_duplicate_names(self, http_request):
         handler.provider.can_duplicate_names.assert_called_once_with()
 
     @pytest.mark.asyncio
-    async def test_postvalidate_put_cant_duplicate_names_and_naming_conflict(self, http_request):
+    async def test_postvalidate_put_cant_duplicate_names_and_naming_conflict(self, http_request,
+                                                                             mock_file_metadata):
 
         handler = mock_handler(http_request)
         handler.path = WaterButlerPath('/Folder1/')
         handler.kind = 'folder'
         handler.provider.can_duplicate_names = mock.Mock(return_value=False)
         handler.get_query_argument = mock.Mock(return_value='child!')
-        handler.provider.exists = MockCoroutine(side_effect=[False, True])
+        handler.provider.exists = MockCoroutine(side_effect=[False, mock_file_metadata])
 
         with pytest.raises(exceptions.NamingConflict) as exc:
             await handler.postvalidate_put()
 
-        assert exc.value.message == 'Cannot complete action: file or folder "child!" already ' \
-                                    'exists in this location'
+        assert json.loads(exc.value.message)['message'] == ('Cannot complete action: file or folder '
+                                                            '"child!" already exists in this location')
 
         handler.provider.can_duplicate_names.assert_called_once_with()
         handler.get_query_argument.assert_called_once_with('name', default=None)

waterbutler/core/exceptions.py

@@ -221,9 +221,13 @@ def __init__(self, name):
 
 
 class NamingConflict(ProviderError):
-    def __init__(self, name):
-        super().__init__('Cannot complete action: file or folder "{}" already exists in this '
-                         'location'.format(name), code=HTTPStatus.CONFLICT, is_user_error=True)
+    def __init__(self, name, extant=None):
+        message = {
+            'message': 'Cannot complete action: file or folder "{}" already exists in this location'.format(name),
+            'data': extant,
+        }
+
+        super().__init__(message, code=HTTPStatus.CONFLICT, is_user_error=True)
 
 
 class ProviderNotFound(ProviderError):

waterbutler/core/provider.py

@@ -653,7 +653,10 @@ async def handle_name_conflict(self,
         if (not exists and not exists == []) or conflict == 'replace':
             return path, exists  # type: ignore
         if conflict == 'warn':
-            raise exceptions.NamingConflict(path.name)
+            raise exceptions.NamingConflict(
+                path.name,
+                extant={} if type(exists) is list else exists.serialized(),
+            )
 
         while True:
             path.increment_name()

waterbutler/server/api/v1/provider/create.py

@@ -62,7 +62,10 @@ async def postvalidate_put(self):
 
             my_type_exists = await self.provider.exists(validated_target_path)
             if not isinstance(my_type_exists, bool) or my_type_exists:
-                raise exceptions.NamingConflict(self.target_path.name)
+                raise exceptions.NamingConflict(
+                    self.target_path.name,
+                    extant=my_type_exists.json_api_serialized(self.resource),
+                )
 
             if not self.provider.can_duplicate_names():
                 target_flipped = self.path.child(self.childs_name, folder=(self.kind != 'folder'))