How can I speed up or perftest context management in Google cloud-ndb library?

Question

I'm in the process of migrating an app running in the Google App Engine Python 2.7 Standard Environment from the built-in NDB to library to the newer cloud-ndb library (prior to a migration to Python 3). The new library requires context for all NDB calls, and after some research and conversation with others on an appengine email list I ran with an approach that enters the context in unittest setUp() and tearDown(). All of my test files derive from a shim base test class.

#speed_test.py
from test._base_test import MyTestCase

class SpeedTest(MyTestCase):
  def test_simple(self):
    string = 'string'
    self.assertEqual('string', string)

#_base_test.py
import requests
import unittest
import webapp2

from google.cloud import ndb


class MyTestCase(unittest.TestCase):
  def setUp(self):
    self.testapp = webapp2.WSGIApplication([])
    # clear datastore
    requests.post('http://localhost:8089/reset')
    self.ndb_context = ndb.Client().context()
    self.ndb_context.__enter__()

  def tearDown(self):
    self.ndb_context.__exit__(None, None, None)
    mock.patch.stopall()

The problem is that entering the context this way adds a little under 2 seconds to each one of my tests. That's mildly irritating for my test files with a dozen or fewer tests, but our full test suite has 681 tests and this speed just isn't feasible.

The above simple speed test should take a fraction of a second to complete, but it consistently runs in 1.7s or more. If I comment out self.ndb_context = ndb.Client().context() and self.ndb_context.__enter__(), it drops down to about 0.003s.

This feels like a long time for the context manager to run but I'm not sure how to do debug performance further at this point. I'm happy to take suggestions on a better approach or means to debug what's happening here so I can file an issue w/ the library if needed. Thanks!

Answer 1

May be you should enter the context only once instead of for every test. Try it again but entering the context using the methods setUpClass and tearDownClass instead of setUp and tearDown. You will find these methods on unittest's documentation.