[tools/perf] Add test for return_code of benchmark_runner

Prevent issues like crbug.com/985712 happening again.

Bug: 990472
Bug: 985712
Change-Id: I6cfa17ec39076f17b6a3bf35b0430f778c05d5ae
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1736896Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Commit-Queue: Caleb Rouleau <crouleau@chromium.org>
Auto-Submit: Juan Antonio Navarro Pérez <perezju@chromium.org>
Cr-Commit-Position: refs/heads/master@{#685376}

tools/perf/core/benchmark_runner.py

@@ -14,9 +14,9 @@ from core import results_processor
 from telemetry import command_line
 
 
-def main(config):
+def main(config, args=None):
   options = command_line.ParseArgs(
-      environment=config,
+      environment=config, args=args,
       results_arg_parser=results_processor.ArgumentParser())
   results_processor.ProcessOptions(options)
   run_return_code = command_line.RunCommand(options)

tools/perf/core/benchmark_runner_unittest.py

+# Copyright 2019 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import unittest
+
+import mock
+
+from core import benchmark_runner
+
+
+def _FakeParseArgs(environment, args, results_arg_parser):
+  del environment  # Unused.
+  options, _ = results_arg_parser.parse_known_args(args)
+  return options
+
+
+class BenchmarkRunnerUnittest(unittest.TestCase):
+  def testMain_returnCode(self):
+    """Test that benchmark_runner.main() respects return code from Telemetry."""
+    # TODO(crbug.com/985712): Ideally we should write a more "integration" kind
+    # of test, where we don't mock out the Telemetry command line. This is
+    # hard to do now, however, because we need a way to convert the browser
+    # selection done by the test runner, back to a suitable --browser arg for
+    # the command line below. Namely, we need an equivalent of
+    # options_for_unittests.GetCopy() that returns a list of string args
+    # rather than the parsed options object.
+    config = mock.Mock()
+    with mock.patch('core.benchmark_runner.command_line') as telemetry_cli:
+      telemetry_cli.ParseArgs.side_effect = _FakeParseArgs
+      telemetry_cli.RunCommand.return_value = 42
+
+      # Note: For now we pass `--output-format none` and a non-existent output
+      # dir to prevent the results processor from processing any results.
+      return_code = benchmark_runner.main(config, [
+          'run', 'some.benchmark', '--browser', 'stable',
+          '--output-dir', '/does/not/exist', '--output-format', 'none'])
+      self.assertEqual(return_code, 42)