[Telemetry] Move TestStreamOutput to unittest_util.

Motivation: when I make benchmark_runner._PrintBenchmarkList a public method,
I want to provide unittest coverage for the method. I would want to reuse the
logic of TestStreamOutput for writing that unittest.

BUG=482090

Review URL: https://codereview.chromium.org/1112773003

Cr-Commit-Position: refs/heads/master@{#327610}

tools/telemetry/telemetry/results/base_test_results_unittest.py

@@ -7,19 +7,6 @@ import unittest
 from telemetry.core import exceptions
 
 
-class TestOutputStream(object):
-
-  def __init__(self):
-    self.output_data = []
-
-  def write(self, data):
-    assert isinstance(data, str)
-    self.output_data.append(data)
-
-  def flush(self):
-    pass
-
-
 class BaseTestResultsUnittest(unittest.TestCase):
 
   def CreateException(self):

tools/telemetry/telemetry/results/gtest_progress_reporter_unittest.py

@@ -11,6 +11,7 @@ from telemetry.results import base_test_results_unittest
 from telemetry.results import gtest_progress_reporter
 from telemetry.results import page_test_results
 from telemetry.unittest_util import simple_mock
+from telemetry.unittest_util import stream
 from telemetry.value import failure
 from telemetry.value import skip
 
@@ -31,7 +32,7 @@ class GTestProgressReporterTest(
     super(GTestProgressReporterTest, self).setUp()
     self._mock_timer = simple_mock.MockTimer(gtest_progress_reporter)
 
-    self._output_stream = base_test_results_unittest.TestOutputStream()
+    self._output_stream = stream.TestOutputStream()
     self._reporter = gtest_progress_reporter.GTestProgressReporter(
         self._output_stream)
 

tools/telemetry/telemetry/unittest_util/gtest_progress_reporter_unittest.py

@@ -8,6 +8,7 @@ import unittest
 from telemetry.core import exceptions
 from telemetry.unittest_util import gtest_progress_reporter
 from telemetry.unittest_util import simple_mock
+from telemetry.unittest_util import stream
 
 
 try:
@@ -23,21 +24,6 @@ class TestFoo(unittest.TestCase):
     pass
 
 
-class TestOutputStream(object):
-  def __init__(self):
-    self._output_data = []
-
-  @property
-  def output_data(self):
-    return ''.join(self._output_data)
-
-  def write(self, data):
-    self._output_data.append(data)
-
-  def flush(self):
-    pass
-
-
 class TestResultWithSuccesses(unittest.TestResult):
   def __init__(self):
     super(TestResultWithSuccesses, self).__init__()
@@ -51,7 +37,7 @@ class TestResultWithSuccesses(unittest.TestResult):
 class GTestProgressReporterTest(unittest.TestCase):
   def setUp(self):
     super(GTestProgressReporterTest, self).setUp()
-    self._stream = TestOutputStream()
+    self._stream = stream.TestOutputStream()
     self._formatter = gtest_progress_reporter.GTestProgressReporter(
         self._stream)
 

tools/telemetry/telemetry/unittest_util/stream.py

@@ -0,0 +1,18 @@
+# Copyright 2015 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.
+
+
+class TestOutputStream(object):
+  def __init__(self):
+    self._output_data = []
+
+  @property
+  def output_data(self):
+    return ''.join(self._output_data)
+
+  def write(self, data):
+    self._output_data.append(data)
+
+  def flush(self):
+    pass