mini-snapshot

A small (<400 lines of code) snapshot testing library for python's unittest. This is a work in progress right now.

Usage

import unittest
from mini_snapshot import SnapshotTestCase

class MySnapshotTest(SnapshotTestCase):
    def test_something(self):
        value = ...  # code to test here
        # test that `value` matches the snapshot
        self.assertMatchesSnapshot(value)

Features

• Working snapshot testing library
• Updating snapshots by setting environment variable PY_SNAPSHOTTEST_UPDATE=1
• It shouldn't cause any arbitrary code execution even if the snapshots aren't trusted
• Customizable snapshot formatting: define _format_snapshot_ (single underscores, not double) on a class like you would do with __repr__
• Works on python 3.10+
• Cleaning unused snapshots in the .snapshots directory

Future possible features (roughly largest -> smallest priority)

• Make it work on classes without a __repr__
• Put it on pypi so that it can be installed easily with pip
• Improve cleaning unused snapshots (e.g. when whole class disappears) - requires custom runner
• Only write snapshots if the rest of the test passes? - requires custom runner to do properly
• Perhaps a CLI so you don't have to fiddle with environment variables
• Interactive mode like jest