Fix bug if application does not specify audience

[djw8605]

If the application does not specify an audience, but the token does, then throw an InvalidAudienceError.

[coveralls]

Coverage remained the same at 100.0% when pulling 7230521 on djw8605:aud-none into 9d98078 on jpadilla:master.

[coveralls]

Coverage remained the same at 100.0% when pulling 7230521 on djw8605:aud-none into 9d98078 on jpadilla:master.

[coveralls]

Coverage remained the same at 100.0% when pulling 8be2680 on djw8605:aud-none into 9d98078 on jpadilla:master.

[jpadilla]

@djw8605 need a bit more info on this. Did something break for you on v1.6.0?

[djw8605]

Hi, yes. When the application does not specify an audience, but the token does, it used to throw an InvalidAudienceError exception. With the most recent version 1.6.0, it now errors out on an iterator:

>       if not any(aud in audience_claims for aud in audience):
E       TypeError: 'NoneType' object is not iterable

blah/lib/python2.7/site-packages/jwt/api_jwt.py:183: TypeError

[jpadilla]

@djw8605 thanks! Can we update the exception string to Invalid audience so it matches previous behavior?

v1.5.3

>>> encoded = jwt.encode({'aud': 'urn:me'}, 'secret', algorithm='HS256')
>>> encoded
b'eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJhdWQiOiJ1cm46bWUifQ.ol7vXY-pDNSVsek4c6oLsfmgncn3t4r8XtJSAog7lh4'
>>> jwt.decode(encoded, 'secret', algorithms=['HS256'])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/jpadilla/.local/share/virtualenvs/pyjwt-stuff-diVMP3qf/lib/python3.6/site-packages/jwt/api_jwt.py", line 90, in decode
    self._validate_claims(payload, merged_options, **kwargs)
  File "/Users/jpadilla/.local/share/virtualenvs/pyjwt-stuff-diVMP3qf/lib/python3.6/site-packages/jwt/api_jwt.py", line 126, in _validate_claims
    self._validate_aud(payload, audience)
  File "/Users/jpadilla/.local/share/virtualenvs/pyjwt-stuff-diVMP3qf/lib/python3.6/site-packages/jwt/api_jwt.py", line 181, in _validate_aud
    raise InvalidAudienceError('Invalid audience')
jwt.exceptions.InvalidAudienceError: Invalid audience

v1.6.0

>>> encoded = jwt.encode({'aud': 'urn:me'}, 'secret', algorithm='HS256')
>>> encoded
b'eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJhdWQiOiJ1cm46bWUifQ.ol7vXY-pDNSVsek4c6oLsfmgncn3t4r8XtJSAog7lh4'
>>> jwt.decode(encoded, 'secret', algorithms=['HS256'])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/jpadilla/.local/share/virtualenvs/pyjwt-stuff-diVMP3qf/lib/python3.6/site-packages/jwt/api_jwt.py", line 89, in decode
    self._validate_claims(payload, merged_options, **kwargs)
  File "/Users/jpadilla/.local/share/virtualenvs/pyjwt-stuff-diVMP3qf/lib/python3.6/site-packages/jwt/api_jwt.py", line 125, in _validate_claims
    self._validate_aud(payload, audience)
  File "/Users/jpadilla/.local/share/virtualenvs/pyjwt-stuff-diVMP3qf/lib/python3.6/site-packages/jwt/api_jwt.py", line 183, in _validate_aud
    if not any(aud in audience_claims for aud in audience):
TypeError: 'NoneType' object is not iterable

[jpadilla]

Update exception message to Invalid audience so it matches previous behavior.

[jpadilla]

Add [336]: https://github.com/jpadilla/pyjwt/pull/336 towards the end of the file.

[djw8605]

@jpadilla changes made.

[jpadilla]

@djw8605 thanks! I'll try to release v1.6.1 soon.