Add json test results format support for SwarmingIsolatedScriptTest

scripts/slave/recipe_modules/swarming/tests/collect_gtest_task_test.py

Index: scripts/slave/recipe_modules/swarming/tests/collect_gtest_task_test.py
diff --git a/scripts/slave/recipe_modules/swarming/tests/collect_gtest_task_test.py b/scripts/slave/recipe_modules/swarming/tests/collect_gtest_task_test.py
index 4df50baf01e6c62b066d0ce921c495c6c8e436d3..c47bb9e6647d2edaa6817e1753e2f6212ff49665 100755
--- a/scripts/slave/recipe_modules/swarming/tests/collect_gtest_task_test.py
+++ b/scripts/slave/recipe_modules/swarming/tests/collect_gtest_task_test.py
@@ -341,6 +341,25 @@ class MergeShardResultsTest(auto_stub.TestCase):
     self.assertEqual(GOOD_GTEST_JSON_MERGED, merged)
     self.assertEqual('', stdout)
 
+  def test_merged_json_result_ok(self):
+    self.stage({
+      'summary.json': {'shards': [{'dummy': 0}, {'dummy': 0}, {'dummy': 0}]},
+      '0/output.json': GOOD_JSON_TEST_RESULT_0,
+      '1/output.json': GOOD_JSON_TEST_RESULT_1,
+      '2/output.json': GOOD_JSON_TEST_RESULT_2,
+    })
+    merged, stdout = self.call()
+    merged['swarming_summary'] = {
+      'shards': [{
+        'outputs_ref': {
+          'view_url': 'blah',
+        },
+      }],
+    }
+    self.assertEqual(GOOD_JSON_TEST_RESULT_MERGED, merged)
+    self.assertEqual('', stdout)
+
+
   def test_missing_summary_json(self):
     # summary.json is missing, should return None and emit warning.
     merged, output = self.call()