cassette 0.1.4

Cassette is a testing tool that stores external HTTP request in YAML file.

• The first time you run your tests, cassette will store all the external requests response in a YAML file.

• Next time you run your tests, cassette will fetch those responses from the YAML file. You can now run your tests while being offline.

import urllib2

import cassette


def test_get_root_domains():
    """Get the root domains."""

    with cassette.play("data/responses.yaml"):

        # If the request is not already stored in responses.yaml, cassette
        # will request the URL and store its response in the file.
        r = urllib2.urlopen("http://www.internic.net/domain/named.root")

        # This time, the request response must be in the file. The external
        # request is not made. cassette retrieves the response from the
        # file.
        r = urllib2.urlopen("http://www.internic.net/domain/named.root")

    assert "A.ROOT-SERVERS.NET" in r.read(10000)

Installation

Locally:

$ python setup.py develop

Via PyPi:

$ pip install cassette

Usage

cassette provides a play context:

import cassette

with cassette.play("./data/responses.yaml"):
    urllib2.urlopen("http://...")

Any urllib2.urlopen request happening in this context will go through cassette’s mocked version of urlopen.

You can also setup the context manually:

import cassette

cassette.insert("./data/responses.yaml")
urllib2.urlopen("http://...")
cassette.eject()

Running cassette tests

Install requirements:

$ pip install -r requirements-dev.txt

Run tests:

$ fab test

Similar libraries

• vcrpy: great library but you can store only one request per YAML file…

• vcr: in Ruby

Limitations

This package should be considered alpha:

• Only tested with urllib2

• Should not work with urllib and requests

• The format used is not compatible with vcr or vcrpy

• Only tested with Python 2.7

• File format may change.

License

cassette is available under the MIT License.