[owners] Use new API to list owners for file

This change implements ListOwnersForFile using gerrit's REST API in owners_client.py
Change-Id: Ic454dcd89a8f00f6b9e913e6b8ee9e1169581b38
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2583327
Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Gavin Mak <gavinmak@google.com>

gerrit_util.py

@@ -770,6 +770,23 @@ def SetCommitMessage(host, change, description, notify='ALL'):
         'in change %s' % change)
 
 
+def GetOwnersForFile(host, project, branch, path, limit=100,
+                     o_params=('DETAILS',)):
+  """Gets information about owners attached to a file."""
+  path = 'projects/%s/branches/%s/code_owners/%s' % (
+      urllib.parse.quote(project, ''),
+      urllib.parse.quote(branch, ''),
+      urllib.parse.quote(path, ''))
+  q = []
+  if limit:
+    q.append('n=%d' % limit)
+  if o_params:
+    q.extend(['o=%s' % p for p in o_params])
+  if q:
+    path = '%s?%s' % (path, '&'.join(q))
+  return ReadHttpJsonResponse(CreateHttpConn(host, path))
+
+
 def GetReviewers(host, change):
   """Gets information about all reviewers attached to a change."""
   path = 'changes/%s/reviewers' % change

owners_client.py

@@ -194,3 +194,16 @@ class DepotToolsClient(OwnersClient):
           [f for f in files if os.path.basename(f) == 'OWNERS'])
     except Exception as e:
       raise InvalidOwnersConfig('Error parsing OWNERS files:\n%s' % e)
+
+
+class GerritClient(OwnersClient):
+  """Implement OwnersClient using OWNERS REST API."""
+  def __init__(self, host):
+    super(GerritClient, self).__init__(host)
+
+  def ListOwnersForFile(self, project, branch, path):
+    # GetOwnersForFile returns a list of account details sorted by order of
+    # best reviewer for path. If code owners have the same score, the order is
+    # random.
+    data = gerrit_util.GetOwnersForFile(self._host, project, branch, path)
+    return [d['account']['email'] for d in data]

tests/owners_client_test.py

@@ -63,6 +63,27 @@ def _get_change():
 
 
 
+def _get_owners():
+  return [
+    {
+      "account": {
+        "email": 'approver@example.com'
+      }
+    },
+    {
+      "account": {
+        "email": 'reviewer@example.com'
+      },
+    },
+    {
+      "account": {
+        "email": 'missing@example.com'
+      },
+    }
+  ]
+
+
+
 class DepotToolsClientTest(unittest.TestCase):
   def setUp(self):
     self.repo = filesystem_mock.MockFileSystem(files={
@@ -118,6 +139,18 @@ class DepotToolsClientTest(unittest.TestCase):
       self.client.ValidateOwnersConfig('changeid')
 
 
+class GerritClientTest(unittest.TestCase):
+  def setUp(self):
+    self.client = owners_client.GerritClient('host')
+
+  @mock.patch('gerrit_util.GetOwnersForFile', return_value=_get_owners())
+  def testListOwners(self, get_owners_mock):
+    self.assertEquals(
+        ['approver@example.com', 'reviewer@example.com', 'missing@example.com'],
+        self.client.ListOwnersForFile('project', 'branch',
+                                      'bar/everyone/foo.txt'))
+
+
 class TestClient(owners_client.OwnersClient):
   def __init__(self, host, owners_by_path):
     super(TestClient, self).__init__(host)