Add support for py3 presubmit

Depot tools git cl presubmit supports py2 and py3. However, presumbit
recipe only runs py2. This patch adds support for running py3 presubmit
checks too.

Bug: 1214829
Recipe-Nontrivial-Roll: build
Change-Id: I089460eaf65d4b6f1238eea13eb087fadb21cad5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2934371Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>

recipes/README.recipes.md

@@ -784,7 +784,7 @@ Raises:
 
 Returns a presubmit step.
 
-— **def [execute](/recipes/recipe_modules/presubmit/api.py#78)(self, bot_update_step, skip_owners=False):**
+— **def [execute](/recipes/recipe_modules/presubmit/api.py#100)(self, bot_update_step, skip_owners=False):**
 
 Runs presubmit and sets summary markdown if applicable.
 
@@ -795,7 +795,7 @@ Args:
 Returns:
   a RawResult object, suitable for being returned from RunSteps.
 
-— **def [prepare](/recipes/recipe_modules/presubmit/api.py#43)(self):**
+— **def [prepare](/recipes/recipe_modules/presubmit/api.py#65)(self):**
 
 Sets up a presubmit run.
 

recipes/recipe_modules/presubmit/api.py

@@ -38,7 +38,29 @@ class PresubmitApi(recipe_api.RecipeApi):
         kwargs['wrapper'] = ('rdb', 'stream', '--')
       step_data = self.m.python(
           name, self.presubmit_support_path, presubmit_args, **kwargs)
-      return step_data.json.output
+      output = step_data.json.output or {}
+      if self.m.step.active_result.retcode != 0:
+        return output
+
+      # Run with vpython3 directly
+      del (kwargs['venv'])
+      presubmit_args = list(args) + [
+          '--json_output',
+          self.m.json.output(),
+      ]
+      step_data = self.m.step(name + " py3",
+                              ['vpython3', self.presubmit_support_path] +
+                              presubmit_args, **kwargs)
+      output2 = step_data.json.output or {}
+
+      # combine outputs
+      for key in output:
+        if key in output2:
+          output[key] += output2[key]
+          del (output2[key])
+      for key in output2:
+        output[key] = output2[key]
+      return output
 
   def prepare(self):
     """Sets up a presubmit run.

recipes/recipe_modules/presubmit/examples/full.expected/basic.json

@@ -21,6 +21,28 @@
       "@@@STEP_LOG_END@json.output@@@"
     ]
   },
+  {
+    "cmd": [
+      "vpython3",
+      "RECIPE_REPO[depot_tools]/presubmit_support.py",
+      "--json_output",
+      "/path/to/tmp/json"
+    ],
+    "env_suffixes": {
+      "DEPOT_TOOLS_UPDATE": [
+        "0"
+      ],
+      "PATH": [
+        "RECIPE_REPO[depot_tools]"
+      ]
+    },
+    "name": "presubmit py3",
+    "~followup_annotations": [
+      "@@@STEP_LOG_END@json.output (invalid)@@@",
+      "@@@STEP_LOG_LINE@json.output (exception)@No JSON object could be decoded@@@",
+      "@@@STEP_LOG_END@json.output (exception)@@@"
+    ]
+  },
   {
     "name": "$result"
   }

recipes/recipe_modules/presubmit/tests/execute.py

@@ -121,6 +121,56 @@ def GenTests(api):
           Expected "," after item in list
           ```
 
+          #### To see notifications and warnings, look at the stdout of the presubmit step.
+        ''').strip()) + api.post_process(post_process.DropExpectation))
+  yield (
+      api.test('failure py3') + api.runtime(is_experimental=False) +
+      api.buildbucket.try_build(project='infra') + api.step_data(
+          'presubmit py3',
+          api.json.output(
+              {
+                  'errors': [{
+                      'message': 'Missing LGTM',
+                      'long_text': 'Here are some suggested OWNERS: fake@',
+                      'items': [],
+                      'fatal': True
+                  }, {
+                      'message': 'Syntax error in fake.py',
+                      'long_text': 'Expected "," after item in list',
+                      'items': [],
+                      'fatal': True
+                  }],
+                  'notifications': [{
+                      'message': 'If there is a bug associated please add it.',
+                      'long_text': '',
+                      'items': [],
+                      'fatal': False
+                  }],
+                  'warnings': [{
+                      'message': 'Line 100 has more than 80 characters',
+                      'long_text': '',
+                      'items': [],
+                      'fatal': False
+                  }]
+              },
+              retcode=1)) + api.post_process(post_process.StatusFailure) +
+      api.post_process(
+          post_process.ResultReason,
+          textwrap.dedent(u'''
+          #### There are 2 error(s), 1 warning(s), and 1 notifications(s). Here are the errors:
+
+          **ERROR**
+          ```
+          Missing LGTM
+          Here are some suggested OWNERS: fake@
+          ```
+
+          **ERROR**
+          ```
+          Syntax error in fake.py
+          Expected "," after item in list
+          ```
+
           #### To see notifications and warnings, look at the stdout of the presubmit step.
         ''').strip()) + api.post_process(post_process.DropExpectation))
 
@@ -213,3 +263,25 @@ def GenTests(api):
          api.post_process(post_process.StatusException) +
          api.post_process(post_process.ResultReason, bug_msg) +
          api.post_process(post_process.DropExpectation))
+
+  yield (api.test('warnings-merged') + api.runtime(is_experimental=False) +
+         api.buildbucket.try_build(project='infra') + api.step_data(
+             'presubmit',
+             api.json.output({
+                 'errors': [],
+                 'notifications': [],
+                 'warnings': [{
+                     'message': 'warning py2'
+                 }]
+             }),
+         ) + api.step_data(
+             'presubmit py3',
+             api.json.output({
+                 'errors': [],
+                 'extra': [],
+                 'warnings': [{
+                     'message': 'warning py3'
+                 }]
+             }),
+         ) + api.post_process(post_process.StatusSuccess) +
+         api.post_process(post_process.DropExpectation))