Disable database access when writing unit tests in Django

Consider this curio:

import mock
from django.utils.functional import curry

no_database = curry(
    mock.patch, 'django.db.backends.util.CursorWrapper',
    Mock(side_effect=RuntimeError("Using the database is not permitted")))

This snippet creates a decorator that can wrap a test case or method and raises an exception if the database is accessed. This can be useful if you’re a puritan about true unit tests.

Use by wrapping a TestCase subclass:

from django.test import TestCase

@no_database()
class UnitTestCase(TestCase):
    ...

or method:

from django.test import TestCase

class UnitTestCase(TestCase):

    @no_database()
    def test_something(self):
        ...

This snippet is a reformulation of one from Carl Meyer’s excellent ‘Testing and Django’ (about 24 minutes in).

Challenge: create a similar decorator that prevents all file-system access in a test method.

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Tagged with: django, testing, python
Filed in: tips
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