[test] Fix merging of test outcomes

BUG=v8:5238

Review-Url: https://codereview.chromium.org/2216293002
Cr-Commit-Position: refs/heads/master@{#38362}

tools/testrunner/local/testsuite_unittest.py

@@ -43,18 +43,20 @@ class TestSuiteTest(unittest.TestCase):
 
   def test_filter_testcases_by_status_second_pass(self):
     suite = TestSuite('foo', 'bar')
-    suite.tests = [
-      TestCase(suite, 'foo/bar', variant='default'),
-      TestCase(suite, 'foo/bar', variant='stress', flags=['-v']),
-      TestCase(suite, 'baz/bar', variant='default'),
-      TestCase(suite, 'baz/bar', variant='stress', flags=['-v']),
-    ]
+
+    test1 = TestCase(suite, 'foo/bar')
+    test2 = TestCase(suite, 'baz/bar')
 
     # Contrived outcomes from filtering by variant-independent rules.
-    suite.tests[0].outcomes = set(['PREV'])
-    suite.tests[1].outcomes = set(['PREV'])
-    suite.tests[2].outcomes = set(['PREV'])
-    suite.tests[3].outcomes = set(['PREV'])
+    test1.outcomes = set(['PREV'])
+    test2.outcomes = set(['PREV'])
+
+    suite.tests = [
+      test1.CopyAddingFlags(variant='default', flags=[]),
+      test1.CopyAddingFlags(variant='stress', flags=['-v']),
+      test2.CopyAddingFlags(variant='default', flags=[]),
+      test2.CopyAddingFlags(variant='stress', flags=['-v']),
+    ]
 
     suite.rules = {
       'default': {

tools/testrunner/objects/testcase.py

@@ -45,7 +45,7 @@ class TestCase(object):
   def CopyAddingFlags(self, variant, flags):
     copy = TestCase(self.suite, self.path, variant, self.flags + flags,
                     self.override_shell)
-    copy.outcomes = self.outcomes
+    copy.outcomes = set(self.outcomes)
     return copy
 
   def PackTask(self):