Can I add non existing field to form with WebTest?

Question

I am testing a form using WebTest. However, somes fields are created dynamically using JS, and thus these fields are not in the Form. I have an error when I try to set one of these fields:

>>> resp.form['new_field'] = 'value'
or
>>> resp.form.set('new_field', 'value')
or
>>> resp.form.set('new_field', 'value', index=0)
or 
>>> resp.form['new_field'].force_value('value')

*** AssertionError: No field by the name 'new_field' found

Is there a way to create a field ?

Answer 1

Updated @lambacck code to handle file fields as well. pos is required on Python3 as well.

from webtest.forms import Text, File
from webtest import Upload


def add_dynamic_field(form, name, value):
    field_cls = File if isinstance(value, Upload) else Text
    field = field_cls(form, tag='input', name=name, value=value, pos=999)
    form.fields[name] = [field]
    form.field_order.append((name, field))