[depot_tools] Make try-results fetch recent dry-runs

Running git cl try-results fetches the latest patchset which may be a trivial change, e.g. rebase or commit message change.
This change allows try-results to get the result of patchsets equivalent to the latest and returns their results.

Bug: 774179
Change-Id: Iec2fea102597773e24c2e887f19282f14c123e61
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2532899
Reviewed-by: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Gavin Mak <gavinmak@google.com>

git_cl.py

@@ -1722,6 +1722,30 @@ class Changelist(object):
     self.SetPatchset(patchset)
     return patchset
 
+  def GetMostRecentDryRunPatchset(self):
+    """Get patchsets equivalent to the most recent patchset and return
+    the patchset with the latest dry run. If none have been dry run, return
+    the latest patchset."""
+    if not self.GetIssue():
+      return None
+
+    data = self._GetChangeDetail(['ALL_REVISIONS'])
+    patchset = data['revisions'][data['current_revision']]['_number']
+    dry_run = set([int(m['_revision_number'])
+        for m in data.get('messages', [])
+        if m.get('tag', '').endswith('dry-run')])
+
+    for revision_info in sorted(data.get('revisions', {}).values(),
+        key=lambda c: c['_number'], reverse=True):
+      if revision_info['_number'] in dry_run:
+        patchset = revision_info['_number']
+        break
+      if revision_info.get('kind', '') not in \
+          ('NO_CHANGE', 'NO_CODE_CHANGE', 'TRIVIAL_REBASE'):
+        break
+    self.SetPatchset(patchset)
+    return patchset
+
   def AddComment(self, message, publish=None):
     gerrit_util.SetReview(
         self._GetGerritHost(), self._GerritChangeIdentifier(),
@@ -4533,7 +4557,7 @@ def CMDtry_results(parser, args):
 
   patchset = options.patchset
   if not patchset:
-    patchset = cl.GetMostRecentPatchset()
+    patchset = cl.GetMostRecentDryRunPatchset()
     if not patchset:
       parser.error('Code review host doesn\'t know about issue %s. '
                    'No access to issue or wrong issue number?\n'

tests/git_cl_test.py

@@ -2950,9 +2950,13 @@ class CMDTestCaseBase(unittest.TestCase):
       'owner': {'email': 'owner@e.mail'},
       'current_revision': 'beeeeeef',
       'revisions': {
-          'deadbeaf': {'_number': 6},
+          'deadbeaf': {
+            '_number': 6, 
+            'kind': 'REWORK',
+          },
           'beeeeeef': {
               '_number': 7,
+              'kind': 'NO_CODE_CHANGE',
               'fetch': {'http': {
                   'url': 'https://chromium.googlesource.com/depot_tools',
                   'ref': 'refs/changes/56/123456/7'
@@ -2988,6 +2992,9 @@ class CMDTestCaseBase(unittest.TestCase):
     mock.patch(
         'git_cl.Changelist.GetMostRecentPatchset',
         return_value=7).start()
+    mock.patch(
+        'git_cl.Changelist.GetMostRecentDryRunPatchset',
+        return_value=6).start()
     mock.patch(
         'git_cl.Changelist.GetRemoteUrl',
         return_value='https://chromium.googlesource.com/depot_tools').start()
@@ -3075,6 +3082,19 @@ class CMDPresubmitTestCase(CMDTestCaseBase):
 
 class CMDTryResultsTestCase(CMDTestCaseBase):
   _DEFAULT_REQUEST = {
+      'predicate': {
+          "gerritChanges": [{
+              "project": "depot_tools",
+              "host": "chromium-review.googlesource.com",
+              "patchset": 6,
+              "change": 123456,
+          }],
+      },
+      'fields': ('builds.*.id,builds.*.builder,builds.*.status' +
+                 ',builds.*.createTime,builds.*.tags'),
+  }
+
+  _TRIVIAL_REQUEST = {
       'predicate': {
           "gerritChanges": [{
               "project": "depot_tools",
@@ -3096,6 +3116,36 @@ class CMDTryResultsTestCase(CMDTestCaseBase):
         mock.ANY, 'cr-buildbucket.appspot.com', 'SearchBuilds',
         self._DEFAULT_REQUEST)
 
+  def testTrivialCommits(self):
+    self.assertEqual(0, git_cl.main(['try-results']))
+    git_cl._call_buildbucket.assert_called_with(
+        mock.ANY, 'cr-buildbucket.appspot.com', 'SearchBuilds',
+        self._DEFAULT_REQUEST)
+
+    git_cl._call_buildbucket.return_value = {}
+    self.assertEqual(0, git_cl.main(['try-results', '--patchset', '7']))
+    git_cl._call_buildbucket.assert_called_with(
+        mock.ANY, 'cr-buildbucket.appspot.com', 'SearchBuilds',
+        self._TRIVIAL_REQUEST)
+    self.assertEqual([
+        'Successes:',
+        '  bot_success            https://ci.chromium.org/b/103',
+        'Infra Failures:',
+        '  bot_infra_failure      https://ci.chromium.org/b/105',
+        'Failures:',
+        '  bot_failure            https://ci.chromium.org/b/104',
+        'Canceled:',
+        '  bot_canceled          ',
+        'Started:',
+        '  bot_started            https://ci.chromium.org/b/102',
+        'Scheduled:',
+        '  bot_scheduled          id=101',
+        'Other:',
+        '  bot_status_unspecified id=100',
+        'Total: 7 tryjobs',
+        'No tryjobs scheduled.',
+    ], sys.stdout.getvalue().splitlines())
+
   def testPrintToStdout(self):
     self.assertEqual(0, git_cl.main(['try-results']))
     self.assertEqual([