Relands "Adds the metadata optional field to the standard JSON results"

This CL had to be reverted because GPU bots were failing because the
results_merger.py script could not handle the test_name_prefix field
that was still getting populated in the JSON results. This CL will
add the metadata field along side the test_name_prefix field in the
Optional fields list in the results_merger.py script. It also removes
the checking of test_name_prefix in the gpu unit tests because the
test_name_prefix field will be removed from the top level of the
results in a future CL.

Bug: chromium:698902
Change-Id: I4867e60ca5a97d426d5fd1a4de08e26c14d326ae
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1559492
Commit-Queue: Rakib Hasan <rmhasan@google.com>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#649665}

content/test/gpu/gpu_tests/gpu_integration_test_unittest.py

@@ -164,25 +164,16 @@ class GpuIntegrationTestUnittest(unittest.TestCase):
     self.assertEqual(
         self._test_result['tests']['unexpected_test_failure']['actual'],
         'FAIL FAIL')
-    self.assertEqual(
-        self._test_result['test_name_prefix'],
-          'unittest_data.integration_tests.RunTestsWithExpectationsFiles.')
 
   def testDefaultRetryArgumentsinRunGpuIntegrationTests(self):
     self._RunGpuIntegrationTests('run_tests_with_expectations_files')
     self.assertEqual(
         self._test_result['tests']['expected_flaky']['actual'],
         'FAIL FAIL FAIL')
-    self.assertEqual(
-        self._test_result['test_name_prefix'],
-        'unittest_data.integration_tests.RunTestsWithExpectationsFiles.')
 
   def testTestNamePrefixGenerationInRunGpuIntegrationTests(self):
     self._RunGpuIntegrationTests('simple_integration_unittest')
     self.assertIn('expected_failure', self._test_result['tests'])
-    self.assertEqual(
-        self._test_result['test_name_prefix'],
-        'unittest_data.integration_tests.SimpleTest.')
 
   def testWithoutExpectationsFilesGenerateTagsReturnsEmptyList(self):
     # we need to make sure that GenerateTags() returns an empty list if

docs/testing/json_test_results_format.md

@@ -86,9 +86,8 @@ object may appear in any order.
 | `artifact_permanent_location` | string | **Optional.** The URI of the root location where the artifacts are stored. If present, any artifact locations are taken to be relative to this location. Currently only the `gs://` scheme is supported. |
 | `build_number` | string | **Optional.** If this test run was produced on a bot, this should be the build number of the run, e.g., "1234". |
 | `builder_name` | string | **Optional.** If this test run was produced on a bot, this should be the builder name of the bot, e.g., "Linux Tests". |
+| `metadata` | dict | **Optional.** It maps to a dictionary that contains all the key value pairs used as metadata. This dictionary also includes the tags, test name prefix and test expectations file paths used during a test run. |
 | `test_name_prefix` | string | **Optional.** If a prefix was specified to be removed from test names, then that prefix can be placed here. |
-| `expectations_files` | array of strings | **Optional.** If a list of expectations file paths are passed to the test runner, then that list can be placed here. |
-| `tags` | array of strings | **Optional.** If a list of test expectations file tags are passed to the test runner, then that list can be placed here. |
 | `chromium_revision` | string | **Optional.** The revision of the current Chromium checkout, if relevant, e.g. "356123". |
 | `has_pretty_patch` | bool | **Optional, layout test specific, deprecated.** Whether the web tests' output contains PrettyDiff-formatted diffs for test failures. |
 | `has_wdiff` | bool | **Optional, layout test specific, deprecated.** Whether the web tests' output contains wdiff-formatted diffs for test failures. |

testing/merge_scripts/results_merger.py

@@ -26,8 +26,7 @@ OPTIONAL_MATCHING = (
     'pixel_tests_enabled',
     'random_order_seed',
     'test_name_prefix',
-    'tags',
-    'expectations_files'
+    'metadata'
     )
 
 OPTIONAL_IGNORED = (

testing/merge_scripts/results_merger_test.py

@@ -172,6 +172,31 @@ class MergingTest(unittest.TestCase):  # pragma: no cover
         results_merger.merge_tries(
             {'a': {'b': 'A'}}, {'a': {'b': 'C'}})
 
+  def test_merge_test_name_prefix(self):
+    results_merger.merge_test_results(
+        [extend(GOOD_JSON_TEST_RESULT_0, {'test_name_prefix': 'a.b.c'}),
+        extend(GOOD_JSON_TEST_RESULT_1, {'test_name_prefix': 'a.b.c'})])
+
+  def test_merge_test_name_prefix_raises_exception(self):
+    with self.assertRaises(results_merger.MergeException):
+      results_merger.merge_test_results(
+          [extend(GOOD_JSON_TEST_RESULT_0, {'test_name_prefix': 'a.d.c'}),
+          extend(GOOD_JSON_TEST_RESULT_1, {'test_name_prefix': 'a.b.c'})])
+
+  def test_merge_metadata(self):
+    metadata = {'metadata': {'tags': ['foo', 'bar']}}
+    results_merger.merge_test_results(
+        [extend(GOOD_JSON_TEST_RESULT_0, metadata),
+         extend(GOOD_JSON_TEST_RESULT_1, metadata)])
+
+  def test_merge_metadata_raises_exception(self):
+    metadata1 = {'metadata': {'tags': ['foo', 'bar']}}
+    metadata2 = {'metadata': {'tags': ['foo', 'bat']}}
+    with self.assertRaises(results_merger.MergeException):
+      results_merger.merge_test_results(
+          [extend(GOOD_JSON_TEST_RESULT_0, metadata1),
+          extend(GOOD_JSON_TEST_RESULT_1, metadata2)])
+
   def test_merge_json_test_results_nop(self):
     good_json_results = (
         GOOD_JSON_TEST_RESULT_0,