Note: This project is just a fork of the package snapshottest which lives here. It had been mostly abandoned, so I kicked the wheels and got it back in working order. Contributions are welcome!
Snapshot testing is a way to test your APIs without writing actual test cases.
- A snapshot is a single state of your API, saved in a file.
- You have a set of snapshots for your API endpoints.
- Once you add a new feature, you can automatically generate new snapshots for the updated API.
$ pip install pysnap
from pysnap 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)
# Set custom snapshot name: `gpg_response`
my_gpg_response = api.client.get('/me?gpg_key')
self.assertMatchSnapshot(my_gpg_response, 'gpg_response')If you want to update the snapshots automatically you can use the nosetests --snapshot-update.
Check the Unittest example.
def test_mything(snapshot):
"""Testing the API for /me"""
my_api_response = api.client.get('/me')
snapshot.assert_match(my_api_response)
# Set custom snapshot name: `gpg_response`
my_gpg_response = api.client.get('/me?gpg_key')
snapshot.assert_match(my_gpg_response, 'gpg_response')If you want to update the snapshots automatically you can use the --snapshot-update config.
Check the Pytest example.
Add to your settings:
TEST_RUNNER = 'pysnap.django.TestRunner'To create your snapshot test:
from pysnap.django 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)If you want to update the snapshots automatically you can use the python manage.py test --snapshot-update.
Check the Django example.
After cloning this repo and configuring a virtualenv for snapshottest (optional, but highly recommended), ensure dependencies are installed by running:
make installAfter developing, the full test suite can be evaluated by running:
make lint
# and
make testIf you change this README.md, remember to update its README.rst counterpart (used by PyPI), which can be done by running:
make README.rst
For this last step you'll need to have pandoc installed in your machine.
This package is heavily inspired in jest snapshot testing.
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.
A similar approach can be taken when it comes to testing your APIs. Instead of rendering the graphical UI, which would require building the entire app, you can use a test renderer to quickly generate a serializable value for your API response.
