Sending multipart request by aiohttp - multipart

Question

I trying to make test case for my view, and now I would to send mutipart request with user credentials containing user image. I use MultipartWriter but, when I'm trying to read parts, I get part as None. I'm sure that my test case is wrong written.
Thanks for your help, and sorry for my bad english.
My test case:
async def test_users_post(app):
with open('user_photo.jpg', 'rb') as file:
user_data = dict(
name='Test1',
password='Password',
grand=True,
description='Blank',
email='test#test.ru',
file=file
)
with MultipartWriter() as mpwriter:
mpwriter.append_form([(key, value) for key, value in user_data.items()])
response = await app['client'].post('/users', data=mpwriter)
assert response.status == 201
Start lines of view:
async def post(self):
reader = await self.request.multipart()
async with self.request.app['db'].acquire() as conn:
data = {}
while True:
field = await reader.next()
print(field) # field is None here
if not field:
# If not fields were read

Answer 1

Okay I had found way, which doesn't need multipart writer.
Now I user aiohttp.FormData for packing user credentials.
async def test_users_post(app):
form = aiohttp.FormData()
user_data = dict(
name='Test1',
password='Password',
description='Blank',
email='test#test.ru',
)
for key, value in user_data.items():
form.add_field(key, value)
form.add_field('photo', open('user_photo.jpg', 'rb'))
response = await app['client'].post('/users', data=form)
assert response.status == 201