Smoke test for tracing infrastructure in PyAuto

chrome/test/functional/tracing/tracer.py

Index: chrome/test/functional/tracing/tracer.py
diff --git a/chrome/test/functional/tracing/tracer.py b/chrome/test/functional/tracing/tracer.py
new file mode 100644
index 0000000000000000000000000000000000000000..aa8c33d0904e91f44a4ece4f37fad1f813392cc4
--- /dev/null
+++ b/chrome/test/functional/tracing/tracer.py
@@ -0,0 +1,102 @@
+# 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 unittest
+
+import pyauto_tracing
+import pyauto
+import tab_tracker
+from timeline_model import TimelineModel
+
+import os
+
+
+class Tracer:
+  """Allows you to start and stop chrome and system tracing,

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

First sentence should be a one-liner.

Details in next para.

+  and get an instance of a TimelineModel which represents the results from a
+  trace.
+  """
+
+  def __init__(self, browser, tab_tracker):
+    """
+    Args:
+      browser: an instance of a PyUITest
+      tab_tracker: an instance of a TabTracker
+    """
+    self._browser = browser
+    self._tab_tracker = tab_tracker
+    self._tab_uuid = tab_tracker.CreateTab('chrome://tracing')
+
+    # I'm not happy with importing timeline_model_shim.js
+    # here. I'd rather pull it in from within TimelineModelProxy.
+    # tracing_test.js depends on timeline_model_shim.js however.
+    # TODO(eatnumber): Find a way to import timeline_model_shim.js from within

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

Move TODO to line 31

+    # TimelineModelProxy
+    files = ["timeline_model_shim.js", "tracer.js"]

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

use '

+    for fileName in files:
+      fileJs, fd = (None, None)

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

fileJs -> file_js

+      try:

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

do not use try block.

with open(...) as fd:
  fileJS = fd.read()

has the same effect

+        fd = open(os.path.join(os.path.dirname(__file__), fileName), "r")
+        fileJs = fd.read()
+      finally:
+        if fd:
+          fd.close()
+      self._ExecuteJavascript(fileJs);
+
+  def __del__(self):
+    self._tab_tracker.ReleaseTab(self._tab_uuid)
+
+  def _ExecuteJavascript(self, js):
+    return self._browser.ExecuteJavascript(
+      js = js,
+      windex = self._tab_tracker.GetWindowIndex(),
+      tab_index = self._tab_tracker.GetTabIndex(self._tab_uuid)
+    )
+
+  def BeginTracing(self, system_tracing=True):
+    """Start tracing
+
+    Args:
+      system_tracing: whether or not to gather system traces along with chrome
+      traces.
+    """
+    self._ExecuteJavascript(
+      """

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

This needs to be indented by 4 spaces wrt previous line.
Please fix everywhere

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

See my previous comment in timeline_model.py

+        window.domAutomationController.send(
+          window.pyautoRecordTrace(%s)
+        );
+      """ % (
+        "true" if system_tracing else "false"

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

use '

(I'm not pointing it out anymore. Please fix it everywhere in this CL.)

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

Sorry about that. I'll go through and fix every occurrence. My mistake.

+      )
+    )
+
+  def EndTracing(self):
+    """End tracing and return a TimelineModel
+
+    Returns:
+      an instance of a TimelineModel which contains the results of the trace
+    """
+    return TimelineModel(
+      js_executor = self._ExecuteJavascript.__get__(self, Tracer),
+      shim_id = self._ExecuteJavascript(
+        """tracingController.endTracing();"""

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

why """?

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

For consistency with everywhere else I call ExecuteJavascript.

[Nirnimesh, 2012/07/31 21:15:06]

On the contrary, it breaks consistency. """ is supposed to be used for
multi-line strings and docstrings only. In fact, using it for even multi-line
strings is discouraged.

+      )
+    )
+

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

Need another blank line

+class TracerFactory:
+  """A TracerFactory is used to produce a Tracer

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

End with . for consistency

+
+  It's recommended to use the same TracerFactory to produce all Tracers so that
+  the same TabTracker can be used throughout
+
+  Args:
+    browser: an instance of a PyUITest
+  """
+  def __init__(self, browser):
+    self._tab_tracker = tab_tracker.TabTracker(browser)
+    self._browser = browser
+
+  def Produce(self):
+    """Produce an instance of a Tracer"""
+    return Tracer(self._browser, self._tab_tracker)