[Telemetry] Re-add API to tear down state after each story run

telemetry/telemetry/internal/story_runner_unittest.py

Index: telemetry/telemetry/internal/story_runner_unittest.py
diff --git a/telemetry/telemetry/internal/story_runner_unittest.py b/telemetry/telemetry/internal/story_runner_unittest.py
index 55ac8fdef09ca553b9c59a25e5c8e67265cd5a82..a6cd6cf254d2d1755ed2c3e88d573dc8f80d9ad9 100644
--- a/telemetry/telemetry/internal/story_runner_unittest.py
+++ b/telemetry/telemetry/internal/story_runner_unittest.py
@@ -326,6 +326,30 @@ class StoryRunnerTest(unittest.TestCase):
     calls_in_order = GetCallsInOrder() # pylint: disable=no-value-for-parameter
     self.assertEquals(EXPECTED_CALLS_IN_ORDER, calls_in_order)
 
+  def testTearDownStateAfterEachStoryRun(self):
+    class TestSharedStateForTearDown(TestSharedState):
+      num_of_tear_downs = 0
+
+      def RunStory(self, results):
+        pass
+
+      def TearDownState(self):
+        TestSharedStateForTearDown.num_of_tear_downs += 1
+
+    story_set = story_module.StorySet()
+    story_set.AddStory(DummyLocalStory(TestSharedStateForTearDown))
+    story_set.AddStory(DummyLocalStory(TestSharedStateForTearDown))
+    story_set.AddStory(DummyLocalStory(TestSharedStateForTearDown))
+
+    TestSharedStateForTearDown.num_of_tear_downs = 0
+    story_runner.Run(mock.MagicMock(), story_set, self.options, self.results)
+    self.assertEquals(TestSharedStateForTearDown.num_of_tear_downs, 1)
+
+    TestSharedStateForTearDown.num_of_tear_downs = 0
+    story_runner.Run(mock.MagicMock(), story_set, self.options, self.results,
+                     should_tear_down_state_after_each_story_run=True)
+    self.assertEquals(TestSharedStateForTearDown.num_of_tear_downs, 3)
+
   def testTearDownIsCalledOnceForEachStoryGroupWithPageSetRepeat(self):
     self.options.pageset_repeat = 3
     fooz_init_call_counter = [0]