Merge suite and benchmark decorators

tools/perf/benchmarks/benchmark_smoke_unittest.py

 # Copyright 2014 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.
 
 """Run the first page of one benchmark for every module.
 
 Only benchmarks that have a composable measurement are included.
 Ideally this test would be comprehensive, however, running one page
 of every benchmark would run impractically long.
 """
@@ skipping 86 matching lines @@
       pass
 
     method = SmokeTestGenerator(benchmark)
 
     # Make sure any decorators are propagated from the original declaration.
     # (access to protected members) pylint: disable=W0212
     # TODO(dpranke): Since we only pick the first test from every class
     # (above), if that test is disabled, we'll end up not running *any*
     # test from the class. We should probably discover all of the tests
     # in a class, and then throw the ones we don't need away instead.
-    if hasattr(benchmark, '_enabled_strings'):
-      method._enabled_strings = benchmark._enabled_strings
-    if hasattr(benchmark, '_disabled_strings'):
-      method._disabled_strings = benchmark._disabled_strings
+
+    # Merge decorators.
+    for attribute in ['_enabled_strings', '_disabled_strings']:
+      # Do set union of attributes to eliminate duplicates.
+      merged_attributes = list(set(getattr(method, attribute, []) +
+                                   getattr(benchmark, attribute, [])))
+      if merged_attributes:
+        setattr(method, attribute, merged_attributes)
+
+      # Handle the case where the benchmark is Enabled/Disabled everywhere.
+      if (getattr(method, attribute, None) == [] or
+          getattr(benchmark, attribute, None) == []):
+        setattr(method, attribute, [])
+
     setattr(BenchmarkSmokeTest, benchmark.Name(), method)
 
     suite.addTest(BenchmarkSmokeTest(benchmark.Name()))
 
   return suite