how to unit test file upload in django

Question

In my django app, I have a view which accomplishes file upload.The core snippet is like this

...
if  (request.method == 'POST'):
    if request.FILES.has_key('file'):
        file = request.FILES['file']
        with open(settings.destfolder+'/%s' % file.name, 'wb+') as dest:
            for chunk in file.chunks():
                dest.write(chunk)

I would like to unit test the view.I am planning to test the happy path as well as the fail path..ie,the case where the request.FILES has no key 'file' , case where request.FILES['file'] has None..

How do I set up the post data for the happy path?Can somebody tell me?

Answer 1

As mentioned in Django's official documentation:

Submitting files is a special case. To POST a file, you need only provide the file field name as a key, and a file handle to the file you wish to upload as a value. For example:

c = Client()
with open('wishlist.doc') as fp:
    c.post('/customers/wishes/', {'name': 'fred', 'attachment': fp})

---

More Information: How to check if the file is passed as an argument to some function?

While testing, sometimes we want to make sure that the file is passed as an argument to some function.

e.g.

...
class AnyView(CreateView):
    ...
    def post(self, request, *args, **kwargs):
        attachment = request.FILES['attachment']
        # pass the file as an argument
        my_function(attachment)
        ...

In tests, use Python's mock something like this:

# Mock 'my_function' and then check the following:

response = do_a_post_request()

self.assertEqual(mock_my_function.call_count, 1)
self.assertEqual(
    mock_my_function.call_args,
    call(response.wsgi_request.FILES['attachment']),
)

Answer 2

I do something like this for my own event related application but you should have more than enough code to get on with your own use case

import tempfile, csv, os

class UploadPaperTest(TestCase):

    def generate_file(self):
        try:
            myfile = open('test.csv', 'wb')
            wr = csv.writer(myfile)
            wr.writerow(('Paper ID','Paper Title', 'Authors'))
            wr.writerow(('1','Title1', 'Author1'))
            wr.writerow(('2','Title2', 'Author2'))
            wr.writerow(('3','Title3', 'Author3'))
        finally:
            myfile.close()

        return myfile

    def setUp(self):
        self.user = create_fuser()
        self.profile = ProfileFactory(user=self.user)
        self.event = EventFactory()
        self.client = Client()
        self.module = ModuleFactory()
        self.event_module = EventModule.objects.get_or_create(event=self.event,
                module=self.module)[0]
        add_to_admin(self.event, self.user)

    def test_paper_upload(self):
        response = self.client.login(username=self.user.email, password='foz')
        self.assertTrue(response)

        myfile = self.generate_file()
        file_path = myfile.name
        f = open(file_path, "r")

        url = reverse('registration_upload_papers', args=[self.event.slug])

        # post wrong data type
        post_data = {'uploaded_file': i}
        response = self.client.post(url, post_data)
        self.assertContains(response, 'File type is not supported.')

        post_data['uploaded_file'] = f
        response = self.client.post(url, post_data)

        import_file = SubmissionImportFile.objects.all()[0]
        self.assertEqual(SubmissionImportFile.objects.all().count(), 1)
        #self.assertEqual(import_file.uploaded_file.name, 'files/registration/{0}'.format(file_path))

        os.remove(myfile.name)
        file_path = import_file.uploaded_file.path
        os.remove(file_path)

Answer 3

I recommend you to take a look at Django RequestFactory. It's the best way to mock data provided in the request.

Said that, I found several flaws in your code.

• "unit" testing means to test just one "unit" of functionality. So, if you want to test that view you'd be testing the view, and the file system, ergo, not really unit test. To make this point more clear. If you run that test, and the view works fine, but you don't have permissions to save that file, your test would fail because of that.
• Other important thing is test speed. If you're doing something like TDD the speed of execution of your tests is really important. Accessing any I/O is not a good idea.

So, I recommend you to refactor your view to use a function like:

def upload_file_to_location(request, location=None): # Can use the default configured

And do some mocking on that. You can use Python Mock.

PS: You could also use Django Test Client But that would mean that you're adding another thing more to test, because that client make use of Sessions, middlewares, etc. Nothing similar to Unit Testing.

Answer 4

From Django docs on Client.post:

Submitting files is a special case. To POST a file, you need only provide the file field name as a key, and a file handle to the file you wish to upload as a value. For example:

c = Client()
with open('wishlist.doc') as fp:
  c.post('/customers/wishes/', {'name': 'fred', 'attachment': fp})

Answer 5

In Django 1.7 there's an issue with the TestCase wich can be resolved by using open(filepath, 'rb') but when using the test client we have no control over it. I think it's probably best to ensure file.read() returns always bytes.

source: https://code.djangoproject.com/ticket/23912, by KevinEtienne

Without rb option, a TypeError is raised:

TypeError: sequence item 4: expected bytes, bytearray, or an object with the buffer interface, str found

Answer 6

I did something like that :

from django.core.files.uploadedfile import SimpleUploadedFile
from django.test import TestCase
from django.core.urlresolvers import reverse
from django.core.files import File
from django.utils.six import BytesIO

from .forms import UploadImageForm

from PIL import Image
from io import StringIO


def create_image(storage, filename, size=(100, 100), image_mode='RGB', image_format='PNG'):
   """
   Generate a test image, returning the filename that it was saved as.

   If ``storage`` is ``None``, the BytesIO containing the image data
   will be passed instead.
   """
   data = BytesIO()
   Image.new(image_mode, size).save(data, image_format)
   data.seek(0)
   if not storage:
       return data
   image_file = ContentFile(data.read())
   return storage.save(filename, image_file)


class UploadImageTests(TestCase):
   def setUp(self):
       super(UploadImageTests, self).setUp()


   def test_valid_form(self):
       '''
       valid post data should redirect
       The expected behavior is to show the image
       '''
       url = reverse('image')
       avatar = create_image(None, 'avatar.png')
       avatar_file = SimpleUploadedFile('front.png', avatar.getvalue())
       data = {'image': avatar_file}
       response = self.client.post(url, data, follow=True)
       image_src = response.context.get('image_src')

       self.assertEquals(response.status_code, 200)
       self.assertTrue(image_src)
       self.assertTemplateUsed('content_upload/result_image.html')

create_image function will create image so you don't need to give static path of image.

Note : You can update code as per you code. This code for Python 3.6.