Running tests with nested objects in the data input

[rth]

Currently it does not seem possible to run unit-tests on endpoints that accept a nested dictionary as input when using flask with webargs / marshmallow,

Here is a minimal example,

from flask import Flask
from webargs import fields
from webargs.flaskparser import use_args

app = Flask(__name__)

hello_args = { 
    'a': fields.Nested({'name' : fields.Str()})
}

@app.route('/', methods=['POST'])
@use_args(hello_args)
def index(args):
    return 'Hello ' + str(args)

def test_app():
    app.config['TESTING'] = True
    test_app = app.test_client(use_cookies=False)
    test_app.post(data={"a": {"name": "Alice"}})

if __name__ == '__main__':
    app.run()

which runs as expected,

% curl -H "Content-Type: application/json" -X POST \
       -d '{"a":{"name": "Alice"}}' http://localhost:5000  

Hello {'a': {'name': 'Alice'}}%

however if I try running tests on it, the argument parsing fails in werkzeug.test.EnvironBuilder with the following error,

nosetests test.py                                                      
E
======================================================================
ERROR: test.test_app
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/lib64/python3.4/site-packages/nose/case.py", line 198, in runTest
    self.test(*self.arg)
  File "/tmp/test.py", line 26, in test_app
    test_app.post(data={"a": {"name": "Alice"}})
  File "/home/rth/.local/lib64/python3.4/site-packages/werkzeug/test.py", line 788, in post
    return self.open(*args, **kw)
  File "/home/rth/.local/lib64/python3.4/site-packages/flask/testing.py", line 103, in open
    builder = make_test_environ_builder(self.application, *args, **kwargs)
  File "/home/rth/.local/lib64/python3.4/site-packages/flask/testing.py", line 34, in make_test_environ_builder
    return EnvironBuilder(path, base_url, *args, **kwargs)
  File "/home/rth/.local/lib64/python3.4/site-packages/werkzeug/test.py", line 338, in __init__
    self._add_file_from_data(key, value)
  File "/home/rth/.local/lib64/python3.4/site-packages/werkzeug/test.py", line 355, in _add_file_from_data
    self.files.add_file(key, **value)
TypeError: add_file() got multiple values for argument 'name'

----------------------------------------------------------------------
Ran 1 test in 0.011s

FAILED (errors=1)

this uses Python 3.5, flask 0.12 and webargs 1.5.2. Any suggestions on how to address this issue (or possible workarounds) would be much appreciated.

[rth]

As was suggested on the pocoo IRC channel, replacing,

test_app.post(data={"a": {"name": "Alice"}})

with

test_app.post(data=json.dumps({"a": {"name": "Alice"}}),
                content_type='application/json')

fixes this problem (also related SO answers here).

[toonarmycaptain]

I'm having trouble with this issue too. Possibly because the data I'm passing is to be interpreted as forms which are nested, dumping to json and setting the content_type as such doesn't work, or at least doesn't place the data in my forms as I need it to be when the request is processed.

[austinhoag]

I also have the same issue as toonarmycaption. The above fix does not work for me.

[davidism]

https://github.com/pallets/werkzeug/issues/1646

Form data is not nestable, it's always sent as a flat list of keys/values. WTForms accomplishes nesting by applying prefixes to the keys so that it can reconstruct the nesting after loading the flat data. You'll need to provide this same flat data. If you're not using WTForms to read the data (the middle portion of your post), you need to access the same flat keys, Werkzeug doesn't parse it into a nested structure.