Smoke test for tracing infrastructure in PyAuto

chrome/test/functional/tracing/timeline_model.py

+# Copyright (c) 2011 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
+
+def escape_for_quoted_javascript_execution(js):
+    # Poor man's string escape.
+    return js.replace("'", "\\'");
+
+class TimelineModelProxy:
+  def __init__(self, js_executor, shim_id):
+    self._js_executor = js_executor
+    self._shim_id = shim_id
+
+  # Warning: The JSON serialization process removes cyclic references.
+  # TODO(eatnumber) regenerate these cyclic references on deserialization.

[Nirnimesh, 2012/07/30 21:03:51]

Need : after TODO(eatnumber)

+  def _CallModelMethod(self, method_name, *args):
+    result = self._js_executor(
+      """
+        window.timelineModelShims['%s'].invokeMethod('%s', '%s')
+      """ % (
+        self._shim_id,
+        escape_for_quoted_javascript_execution(method_name),
+        escape_for_quoted_javascript_execution(json.dumps(args))
+      )
+    )
+    if result["success"]:
+      return result["data"]
+    # TODO(eatnumber) Make these exceptions more reader friendly.
+    raise Exception(result)
+
+  def __del__(self):
+    self._js_executor(
+      """
+        window.timelineModelShims['%s'] = undefined;
+        window.domAutomationController.send('');
+      """ % self._shim_id
+    )
+
+  def GetAllThreads(self):
+    return self._CallModelMethod("getAllThreads")
+
+  def GetAllCpus(self):
+    return self._CallModelMethod("getAllCpus")
+
+  def GetAllProcesses(self):
+    return self._CallModelMethod("getAllProcesses")
+
+  def GetAllCounters(self):
+    return self._CallModelMethod("getAllCounters")
+
+  def FindAllThreadsNamed(self, name):
+    return self._CallModelMethod("findAllThreadsNamed", name);
+
+# Alias TimelineModel to TimelineModelProxy for convenience.
+TimelineModel = TimelineModelProxy

[Nirnimesh, 2012/07/30 21:03:51]

Why not change line 12 instead?

[Russ Harmon, 2012/07/31 01:11:16]

Because while I don't want authors of tests to know that this is a proxy, it
_is_ a proxy, and so naming the class as such is the most logical and readable
thing to do.

[Nirnimesh, 2012/07/31 20:05:57]

That seems like a good note to put in the docstring. "This is a proxy"
The style guide discourages global vars. In essence that's what you're doing
here. It can be avoided.

[Russ Harmon, 2012/07/31 20:54:18]

How can it be avoided while both keeping a name for the TimelineModelProxy class
illustrative of the fact that this is a proxy, and avoiding having test authors
know that this class is a proxy?

[Nirnimesh, 2012/07/31 21:15:05]

I don't understand your motivation. You want test authors to not know it's a
proxy, yet you want it in the name.
Doesn't calling this out in the class docstring help?