snapshottest 0.2.0

SnapshotTest

Snapshot testing is a way to test your APIs without writing actual test cases.

1. A snapshot is a single state of your API, saved in a file.

2. You have a set of snapshots for your API endpoints.

3. Once you add a new feature, you can generate automatically new snapshots for the updated API.

$ pip install snapshottest

from snapshottest import TestCase

class APITestCase(TestCase):
    def test_api_me(self):
        """Testing the API for /me"""
        my_api_response = api.client.get('/me')
        self.assertMatchSnapshot(my_api_response)

def test_mything(snapshot):
    """Testing the API for /me"""
    my_api_response = api.client.get('/me')
    snapshot.assert_match(my_api_response)

Contributing

After cloning this repo, ensure dependencies are installed by running:

pip install -e ".[test]"

After developing, the full test suite can be evaluated by running:

py.test tests --cov=snapshottest

Notes

This package is heavily insipired in jest snapshot testing.

Reasons for use this package

Most of this content is taken from the Jest snapshot blogpost.

We want to make it as frictionless as possible to write good tests that are useful. We observed that when engineers are provided with ready-to-use tools, they end up writing more tests, which in turn results in stable and healthy code bases.

However engineers frequently spend more time writing a test than the component itself. As a result many people stopped writing tests altogether which eventually led to instabilities.

A typical snapshot test case for a mobile app renders a UI component, takes a screenshot, then compares it to a reference image stored alongside the test. The test will fail if the two images do not match: either the change is unexpected, or the screenshot needs to be updated to the new version of the UI component.