[Telemetry] Add CanRunOnPlatform to story_runner and benchmark class.

telemetry/telemetry/benchmark_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.
 
 import optparse
 import unittest
 
 from telemetry import android
 from telemetry import benchmark
 from telemetry.testing import options_for_unittests
@@ skipping 271 matching lines @@
     parser = optparse.OptionParser()
     benchmark.AddCommandLineArgs(parser)
     options.MergeDefaultValues(parser.get_default_values())
 
     b = TbmBenchmark(None)
     tbm = b.CreatePageTest(options)
     self.assertTrue(tbm._tbm_options.config.enable_atrace_trace)
     self.assertEqual(
         ['string', 'foo', 'stuff', 'bar'],
         tbm._tbm_options.config.atrace_config.categories)
+
+  def testCanRunOnPlatformReturnTrue(self):
+    b = TestBenchmark(story_module.Story(
+        name='test name',
+        shared_state_class=shared_page_state.SharedPageState))
+    # We can pass None for both arguments because it defaults to ALL for
+    # supported platforms, which always returns true.
+    self.assertTrue(b._CanRunOnPlatform(None, None))
+
+  def testCanRunOnPlatformReturnFalse(self):
+    b = TestBenchmark(story_module.Story(
+        name='test name',
+        shared_state_class=shared_page_state.SharedPageState))
+    b.SUPPORTED_PLATFORMS = []
+    # We can pass None for both arguments because we select no platforms as
+    # supported, which always returns false.
+    self.assertFalse(b._CanRunOnPlatform(None, None))