[Culprit-finder] Refactor findit testcase and move it to libs.

appengine/findit/common/findit_testcase.py

-# Copyright 2016 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
-
-from testing_utils import testing
-
-from lib import time_util
-
-
-class FinditTestCase(testing.AppengineTestCase):  # pragma: no cover.
-  # Setup the customized queues.
-  taskqueue_stub_root_path = os.path.join(
-    os.path.dirname(__file__), os.path.pardir)
-
-  def MockPipeline(
-      self, pipeline_class, result, expected_args, expected_kwargs=None):
-    """Mocks a pipeline to return a value and asserts the expected parameters.
-
-    Args:
-      pipeline_class (class): The class of the pipeline to be mocked.
-      result (object): The result to be returned by the pipeline.
-      expected_args (list): The list of positional parameters expected by the
-          pipeline.
-      expected_kwargs (dict): The dict of key-value parameters expected by the
-          pipeline. Default is None.
-    """
-    expected_kwargs = expected_kwargs or {}
-
-    def Mocked_run(_, *args, **kwargs):
-      self.assertEqual(list(args), expected_args)
-      self.assertEqual(kwargs, expected_kwargs)
-      return result
-
-    self.mock(pipeline_class, 'run', Mocked_run)
-
-  def MockUTCNow(self, mocked_utcnow):
-    """Mocks utcnow with the given value for testing."""
-    self.mock(time_util, 'GetUTCNow', lambda: mocked_utcnow)
-
-  def MockUTCNowWithTimezone(self, mocked_utcnow):
-    """Mocks utcnow with the given value for testing."""
-    self.mock(time_util, 'GetUTCNowWithTimezone', lambda: mocked_utcnow)