Telemetry / Devtools TraceHandler: exposes tracing via dev tools.

tools/telemetry/telemetry/tracing_backend_unittest.py

+# Copyright (c) 2012 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 json
+import os
+
+from telemetry import tab_test_case
+from telemetry import util
+
+
+class TracingBackendTest(tab_test_case.TabTestCase):
+  def _StartServer(self):
+    base_dir = os.path.dirname(__file__)
+    self._browser.SetHTTPServerDirectory(os.path.join(base_dir, '..',
+        'unittest_data'))
+
+  def _WaitForAnimationFrame(self):
+    def _IsDone():
+      js_is_done = """done"""
+      return bool(self._tab.runtime.Evaluate(js_is_done))
+    util.WaitFor(_IsDone, 5)
+
+  def testGotTrace(self):
+    self._StartServer()
+    self._browser.StartTracing()
+    self._browser.http_server.UrlOf('image.png')
+    self.assertTrue(self._browser.supports_tracing)
+    self._browser.StopTracing()
+    trace = self._browser.GetTrace()
+    json_trace = json.loads(trace)
+    self.assertTrue('traceEvents' in json_trace)
+    self.assertTrue(json_trace['traceEvents'])