Content-Type and Content-Length are set to empty string in test environment

[f11r]

At the moment in the test environment the Content-Type and Content-Length headers are always set (see

werkzeug/werkzeug/test.py

Line 582 in 40bfd13

'CONTENT_LENGTH': str(content_length or '0'),

), even if not provided by the user. This makes the following calls identical and stops anyone from testing a call without one of these headers:

resp = app_client.post('/v1.0/post_wrong_content_type', data=json.dumps({'some': 'data'}))

resp = app_client.post('/v1.0/post_wrong_content_type', data=json.dumps({'some': 'data'}), 
                       content_type='')

This seems very similar to #1049.

[mitsuhiko]

This is permitted by the WSGI spec:

The following variables must be present, unless their value would be an empty string, in which case they may be omitted, except as otherwise noted below

The contents of any Content-Type fields in the HTTP request. May be empty or absent.

We generally treat missing and set empty the same.