Database data diffing against fixtures for testing
I’m pretty lazy when it comes to writing tests for existing code, however, I’m even lazier when it comes to repetitive manual testing action.
This package aims at de-duplicating the data import tests from django-representatives and django-representatives-votes which is re-used in django-cities-light.
A nice way to test a data import script is to create a source data fixture with a subset of data, ie. with only 10 cities instead of 28K or only 3 european parliament representatives instead of 3600, feed the import function with that and then compare the database state with a django fixture. This looks like what I was used to do:
When a bug is fixed, just add the case to the fixture and repeat the process to create new expected data dumps, use coverage to ensure no case is missed.
With django-dbdiff, I just need to maintain to initial data extract, and test it with Fixture('appname/path/to/fixture', models=[YourModelToTest]).assertNoDiff() in a django.test.TransactionTestCase which has reset_sequences=True:
from django import TransactionTestCase from dbdiff.fixture import Fixture class YourImportTest(test.TransactionTestCase): reset_sequences = True def test_your_import(self): your_import() Fixture('yourapp/tests/yourtest.json', models=[YourModel]).assertNoDiff()
The first time, it will raise a FixtureCreated exception, and the test will fail. This is to inform the user that the test didn’t really run. On the next run though, it will pass.
If any difference is found between the database and the test fixture, then diff() will return the diff as outputed by GNU diff.
See tests and docstrings for crunchy details.
MySQL, SQLite and PostgreSQL, Python 2.7 and 3.4 are supported along with Django 1.7 to 1.10 - it’s always better to support django’s master so that we can upgrade easily when it is released, which is one of the selling points for having 100% coverage.
Install django-dbdiff with pip and add dbdiff to INSTALLED_APPS.
It is interresting to note that a related, perhaps sort-of similar app exists: https://github.com/Griffosx/djmo