I\'m using Flask-Testing for my Flask integration tests. I\'ve got a form that has a file upload for a logo that I\'m trying to write tests for but I keep getting an error sayin
The issue ended up not being that when one adds content_type='multipart/form-data'
to the post
method it expect all values in data
to either be files or strings. There were integers in my data dict which I realised thanks to this comment.
So the end solution ended up looking like this:
def test_edit_logo(self):
"""Test can upload logo."""
data = {'name': 'this is a name', 'age': 12}
data = {key: str(value) for key, value in data.items()}
data['file'] = (io.BytesIO(b"abcdef"), 'test.jpg')
self.login()
response = self.client.post(
url_for('adverts.save'), data=data, follow_redirects=True,
content_type='multipart/form-data'
)
self.assertIn(b'Your item has been saved.', response.data)
advert = Item.query.get(1)
self.assertIsNotNone(item.logo)
You need two things:
1.) content_type='multipart/form-data'
in your .post()
2.) in your data=
pass in file=(BytesIO(b'my file contents'), "file_name.jpg")
A full example:
data = dict(
file=(BytesIO(b'my file contents'), "work_order.123"),
)
response = app.post(url_for('items.save'), content_type='multipart/form-data', data=data)
You can use Werkzeug's FileStorage
(as used by Flask under the hood).
You can mock a file like this:
from werkzeug.datastructures import FileStorage
import io
import json
# Here we are mocking a JSON file called Input.json
my_dict = {"msg": "hello!"}
input_json = json.dumps(my_dict, indent=4).encode("utf-8")
mock_file = FileStorage(
stream=io.BytesIO(input_json),
filename="Input.json",
content_type="application/json",
)
Notice that I use a real file on my server:
tests/assets/my_video.mp4
from werkzeug.datastructures import FileStorage
my_video = os.path.join("tests/assets/my_video.mp4")
my_file = FileStorage(
stream=open(my_video, "rb"),
filename="my_video.mp4",
content_type="video/mpeg",
),
rv = client.post(
"/api/v1/video",
data={
"my_video": my_file,
},
content_type="multipart/form-data"
)
Test to see it returns a response status code of 200:
assert "200" in rv.status
I can then test that the file arrives in a test directory on the server:
assert "my_video.mp4" in os.listdir("tests/my_test_path")
Also note, you need to set the mocked file to None
on teardown otherwise you'll get a ValueError: I/O operation on closed file.
. Below is a Pytest example:
def setup_method(self):
self.mock_file = FileStorage(
stream=io.BytesIO(input_json),
filename="Input.json",
content_type="application/json",
)
def teardown_method(self):
self.mock_file = None
While trying to find a bug in my code I've created a SSCCE for file upload (based on the docs) with a corresponding test based on other answers here. It might be useful for somebody:
app.py:
import base64
import os
import pathlib
import tempfile
import textwrap
import flask
import werkzeug.utils
root = flask.Blueprint('root', __name__)
@root.route('/', methods=['GET', 'POST'])
def upload_file():
if flask.request.method == 'POST':
try:
file = flask.request.files['file']
if not file.filename:
raise LookupError()
filename = werkzeug.utils.secure_filename(file.filename)
file.save(pathlib.Path(flask.current_app.config['UPLOAD_FOLDER'], filename))
flask.flash('File saved!', 'message')
except LookupError:
flask.flash('No file provided!', 'error')
return flask.redirect(flask.url_for('root.upload_file'))
else:
return flask.render_template_string(textwrap.dedent(
'''\
<!doctype html>
<title>Upload new File</title>
{% with messages = get_flashed_messages(with_categories=true) %}{% if messages %}
<ul class=flashes>
{% for category, message in messages %}<li class="{{ category }}">{{ message }}</li>
{% endfor %}
</ul>
{% endif %}{% endwith %}
<h1>Upload new File</h1>
<form method=post enctype=multipart/form-data>
<input type=file name=file>
<input type=submit value=Upload>
</form>
'''
))
def create_app():
app = flask.Flask(__name__)
app.config['UPLOAD_FOLDER'] = tempfile.gettempdir()
app.secret_key = 'change-me'
app.register_blueprint(root)
return app
if __name__ == '__main__':
create_app()
test_app.py:
"""upload tests"""
import base64
import io
import unittest
import werkzeug
import app
# https://raw.githubusercontent.com/mathiasbynens/small/master/jpeg.jpg
SMALLEST_JPEG_B64 = """\
/9j/2wBDAAMCAgICAgMCAgIDAwMDBAYEBAQEBAgGBgUGCQgKCgkICQkKDA8MCgsOCwkJDRENDg8Q
EBEQCgwSExIQEw8QEBD/yQALCAABAAEBAREA/8wABgAQEAX/2gAIAQEAAD8A0s8g/9k=
"""
class BaseTestCase(unittest.TestCase):
def test_save(self):
with app.create_app().test_client() as client:
file = werkzeug.datastructures.FileStorage(
stream=io.BytesIO(base64.b64decode(SMALLEST_JPEG_B64)),
filename="example image.jpg",
content_type="image/jpg",
)
response = client.post(
'/',
data=dict(
file=file,
),
follow_redirects=True,
content_type='multipart/form-data',
)