[Telemetry] Add capability for values to reference external files.

tools/telemetry/telemetry/value/trace_unittest.py

Index: tools/telemetry/telemetry/value/trace_unittest.py
diff --git a/tools/telemetry/telemetry/value/trace_unittest.py b/tools/telemetry/telemetry/value/trace_unittest.py
new file mode 100644
index 0000000000000000000000000000000000000000..70d8dc9e6029f55901084d4390b74f15e8602789
--- /dev/null
+++ b/tools/telemetry/telemetry/value/trace_unittest.py
@@ -0,0 +1,58 @@
+# 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 os
+import shutil
+import unittest
+
+from telemetry.page import page_set
+from telemetry.timeline import timeline_data
+from telemetry.value import trace
+
+class TestBase(unittest.TestCase):
+  def setUp(self):
+    self.page_set = page_set.PageSet(file_path=os.path.dirname(__file__))
+    self.page_set.AddPageWithDefaultRunNavigate("http://www.bar.com/")
+    self.page_set.AddPageWithDefaultRunNavigate("http://www.baz.com/")
+    self.page_set.AddPageWithDefaultRunNavigate("http://www.foo.com/")
+
+  @property
+  def pages(self):
+    return self.page_set.pages
+
+class TimelineDataForTest(timeline_data.TimelineData):
+  def __init__(self):
+    super(TimelineDataForTest, self).__init__()
+    self._event_data = 'foo'
+
+  def Serialize(self, f):
+    f.write(self._event_data)
+    f.flush()
+    os.fsync(f)
+
+  def EventData(self):
+    return self._event_data
+
+
+class ValueTest(TestBase):
+  def testCreateAndCopyAndRead(self):
+    # Windows does not support opening a tempfile twice so we make a copy.
+    v = trace.TraceValue(None, 'bar', TimelineDataForTest())
+    path = v.GetAssociatedFileHandle().GetRelPath('.')
+
+    shutil.copy(path, 'test_create_and_copy_000')
+    f = open('test_create_and_copy_000')
+    s = f.read()
+    f.close()
+    os.remove('test_create_and_copy_000')
+
+    self.assertEqual(s, 'foo')
+
+  def testAsDict(self):
+    v = trace.TraceValue(None, 'bar', TimelineDataForTest())
+    fh_id = v.GetAssociatedFileHandle().id
+
+    d = v.AsDict()
+
+    self.assertEqual(d['file_id'], fh_id)