Django test FileField using test fixtures

Question

I'm trying to build tests for some models that have a FileField. The model looks like this:

class SolutionFile(models.Model):
    '''
    A file from a solution.
    '''
    solution = models.ForeignKey(Solution)
    file = models.FileField(upload_to=make_solution_file_path)

I have encountered two problems:

When saving data to a fixture using ./manage.py dumpdata, the file contents are not saved, only the file name is saved into the fixture. While I find this to be the expected behavior as the file contents are not saved into the database, I'd like to somehow include this information in the fixture for tests.

I have a test case for uploading a file that looks like this:

def test_post_solution_file(self):
    import tempfile
    import os
    filename = tempfile.mkstemp()[1]
    f = open(filename, 'w')
    f.write('These are the file contents')
    f.close()
    f = open(filename, 'r')
    post_data = {'file': f}
    response = self.client.post(self.solution.get_absolute_url()+'add_solution_file/', post_data,
                                follow=True)
    f.close()
    os.remove(filename)
    self.assertTemplateUsed(response, 'tests/solution_detail.html')
    self.assertContains(response, os.path.basename(filename))

While this test works just fine, it leaves the uploaded file in the media directory after finishing. Of course, the deletion could be taken care of in tearDown(), but I was wondering if Django had another way of dealing with this.

One solution I was thinking of was using a different media folder for tests which must be kept synced with the test fixtures. Is there any way to specify another media directory in settings.py when tests are being run? And can I include some sort of hook to dumpdata so that it syncs the files in the media folders?

So, is there a more Pythonic or Django-specific way of dealing with unit tests involving files?

user_114672 · Answer

I've written unit tests for an entire gallery app before, and what worked well for me was using the python tempfile and shutil modules to create copies of the test files in temporary directories and then delete them all afterwards.

The following example is not working/complete, but should get you on the right path:

import os, shutil, tempfile

PATH_TEMP = tempfile.mkdtemp(dir=os.path.join(MY_PATH, 'temp'))

def make_objects():
    filenames = os.listdir(TEST_FILES_DIR)

    if not os.access(PATH_TEMP, os.F_OK):
        os.makedirs(PATH_TEMP)

    for filename in filenames:
        name, extension = os.path.splitext(filename)
        new = os.path.join(PATH_TEMP, filename)
        shutil.copyfile(os.path.join(TEST_FILES_DIR, filename), new)

        #Do something with the files/FileField here

def remove_objects():
    shutil.rmtree(PATH_TEMP)

I run those methods in the setUp() and tearDown() methods of my unit tests and it works great! You've got a clean copy of your files to test your filefield that are reusable and predictable.

user_5305401 · Answer

with pytest and pytest-django, I use this in conftest.py file:

import tempfile
import shutil
from pytest_django.lazy_django import skip_if_no_django
from pytest_django.fixtures import SettingsWrapper


@pytest.fixture(scope='session')
#@pytest.yield_fixture()
def settings():
    """A Django settings object which restores changes after the testrun"""
    skip_if_no_django()

    wrapper = SettingsWrapper()
    yield wrapper
    wrapper.finalize()


@pytest.fixture(autouse=True, scope='session')
def media_root(settings):
    tmp_dir = tempfile.mkdtemp()
    settings.MEDIA_ROOT = tmp_dir
    yield settings.MEDIA_ROOT
    shutil.rmtree(tmp_dir)


@pytest.fixture(scope='session')
def django_db_setup(media_root, django_db_setup):
    print('inject_after')

might be helpful:

Django test FileField using test fixtures

5 Answers