Betamax is a VCR imitation for requests. This will make mocking out requests much easier. It is tested on Travis CI.

Put in a more humorous way: “Betamax records your HTTP interactions so the NSA does not have to.”

Example Use

from betamax import Betamax
from requests import Session
from unittest import TestCase

with Betamax.configure() as config:
    config.cassette_library_dir = 'tests/fixtures/cassettes'

class TestGitHubAPI(TestCase):
    def setUp(self):
        self.session = Session()

    # Set the cassette in a line other than the context declaration
    def test_user(self):
        with Betamax(self.session) as vcr:
            resp = self.session.get('',
                                    auth=('user', 'pass'))
            assert resp.json()['login'] is not None

    # Set the cassette in line with the context declaration
    def test_repo(self):
        with Betamax(self.session).use_cassette('repo'):
            resp = self.session.get(
            assert resp.json()['owner'] != {}

What does it even do?

If you are unfamiliar with VCR, you might need a better explanation of what Betamax does.

Betamax intercepts every request you make and attempts to find a matching request that has already been intercepted and recorded. Two things can then happen:

  1. If there is a matching request, it will return the response that is associated with it.
  2. If there is not a matching request and it is allowed to record new responses, it will make the request, record the response and return the response.

Recorded requests and corresponding responses - also known as interactions - are stored in files called cassettes. (An example cassette can be seen in the examples section of the documentation.) The directory you store your cassettes in is called your library, or your cassette library.

VCR Cassette Compatibility

Betamax can use any VCR-recorded cassette as of this point in time. The only caveat is that python-requests returns a URL on each response. VCR does not store that in a cassette now but we will. Any VCR-recorded cassette used to playback a response will unfortunately not have a URL attribute on responses that are returned. This is a minor annoyance but not something that can be fixed.


You can check out the project board on to see what the status of each issue is.