Support for required with marshmallow and file on pyramid ?

[inkhey]

Currently

In this environmment:

• hapic
• marshmallow
• pyramid.

using input file with schema like:
files = marshmallow.fields.Raw(required=True, description="a file")

Do not work properly because of required = True check:
Without file: normal behavior:

 ❯ http -a [email protected]:[email protected] --form POST http://localhost:6543/api/v2/workspaces/1/files                              
HTTP/1.1 400 Bad Request
Content-Length: 118
Content-Type: application/json
Date: Tue, 03 Sep 2019 08:10:13 GMT
Server: waitress
Set-Cookie:  session_key=f922244fe7632e1503a4d7be19558025db968fcd535240b2ada24e84ad3de217104c1e5b; expires=Mon, 03-Sep-2018 08:10:13 GMT; Path=/; SameSite=Lax

{
    "code": 2001, 
    "details": {
        "files": [
            "Missing data for required field"
        ]
    }, 
    "message": "Validation error of input data"
}

With file: error

 ❯ http -a [email protected]:[email protected] --form POST http://localhost:6543/api/v2/workspaces/1/files files@/home/user/image.jpg
HTTP/1.1 500 Internal Server Error
Content-Length: 107
Content-Type: application/json
Date: Tue, 03 Sep 2019 08:09:04 GMT
Server: waitress
Set-Cookie:  session_key=3046282046ce7ea42286579dc0f77bf2f63b65fb42da3084df764760898a54b71843d46d; expires=Mon, 03-Sep-2018 08:09:05 GMT; Path=/; SameSite=Lax

{
    "code": null, 
    "details": {
        "error_detail": {}
    }, 
    "message": "argument of type 'SimpleFile' is not iterable"
}

Expected

Support required for file in this case too, check also actual support in other framework and serpyco.