Don't crash if there is no description

[asottile]

Resolves #411

[codecov]

Codecov Report

Merging #412 into master will increase coverage by 0.2%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master     #412     +/-   ##
=========================================
+ Coverage   78.08%   78.29%   +0.2%     
=========================================
  Files          14       14             
  Lines         730      737      +7     
  Branches      104      106      +2     
=========================================
+ Hits          570      577      +7     
- Misses        127      128      +1     
+ Partials       33       32      -1

Impacted Files	Coverage Δ
twine/commands/check.py	100% <100%> (ø)	⬆️
twine/wininst.py	31.57% <0%> (ø)	⬆️

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[sigmavirus24]

It would be better if this was done outside of the function call.

It would further seem as though "description" may not be present and if it is present (or perhaps it is always present?) it can be None. The behaviour of metadata seems to be poorly understood by all involved, what do you think about documenting the actual behaviour here. It would be better if everyone after this point in time understood the reason for this change and why it was necessary. The comment in the test is a bit too opaque to provide that understanding.

[asottile]

I was following the precedent from line 89, would you like me to change that one as well?

[sigmavirus24]

Please do. It's not a very good precedent.

[di]

Since all this command does right now is check if the description is valid, perhaps it should give a warning if there is no description value, rather than silently passing? It seems to me like there should be a difference between "this package has provided an empty description" and "this package has not provided a description". The user probably wants to know if the latter is happening.

[merwok]

I agree with the warning or error. For example, I found this bug and PR because twine does not include long_description in generated sdists (pypa/flit#216); if twine had seemed to work I would not have seen the flit problem.

[asottile]

This is pretty special / broken from the setuptools / wheel side. Here's some data:

Checking distribution long/dist/pkg-0.0.0-py3-none-any.whl: 
*******************************************************************************
description: 'long description\n\n\n'
description_content_type: 'text/markdown'
*******************************************************************************

Checking distribution missing/dist/pkg-0.0.0-py3-none-any.whl: 
*******************************************************************************
description: 'UNKNOWN\n\n\n'
description_content_type: None
*******************************************************************************

Checking distribution missing_long/dist/pkg-0.0.0-py3-none-any.whl: 
*******************************************************************************
description: 'UNKNOWN\n\n\n'
description_content_type: 'text/markdown'
*******************************************************************************

Checking distribution missing_type/dist/pkg-0.0.0-py3-none-any.whl: 
*******************************************************************************
description: 'long description\n\n\n'
description_content_type: None
*******************************************************************************

Checking distribution long/dist/pkg-0.0.0.tar.gz: 
*******************************************************************************
description: 'long description'
description_content_type: 'text/markdown'
*******************************************************************************

Checking distribution missing/dist/pkg-0.0.0.tar.gz: 
*******************************************************************************
description: None
description_content_type: None
*******************************************************************************

Checking distribution missing_long/dist/pkg-0.0.0.tar.gz: 
*******************************************************************************
description: None
description_content_type: 'text/markdown'
*******************************************************************************

Checking distribution missing_type/dist/pkg-0.0.0.tar.gz: 
*******************************************************************************
description: 'long description'
description_content_type: None
*******************************************************************************

Things to note here:

• wheel will set the description to 'UNKNOWN\n\n\n' when it is missing
• wheel seems to always add \n\n\n to both the description and content type
• these fields appear to always be present, but are sometimes None

[asottile]

Here's the new behaviour:

$ twine check $(find */dist/* -type f | sort)
Checking distribution long/dist/pkg-0.0.0-py3-none-any.whl: Passed
Checking distribution missing/dist/pkg-0.0.0-py3-none-any.whl: warning: `long_description_content_type` missing.  defaulting to `text/x-rst`.
warning: `long_description` missing.
Passed
Checking distribution missing_long/dist/pkg-0.0.0-py3-none-any.whl: warning: `long_description` missing.
Passed
Checking distribution missing_type/dist/pkg-0.0.0-py3-none-any.whl: warning: `long_description_content_type` missing.  defaulting to `text/x-rst`.
Passed
Checking distribution long/dist/pkg-0.0.0.tar.gz: Passed
Checking distribution missing/dist/pkg-0.0.0.tar.gz: warning: `long_description_content_type` missing.  defaulting to `text/x-rst`.
warning: `long_description` missing.
Passed
Checking distribution missing_long/dist/pkg-0.0.0.tar.gz: warning: `long_description` missing.
Passed
Checking distribution missing_type/dist/pkg-0.0.0.tar.gz: warning: `long_description_content_type` missing.  defaulting to `text/x-rst`.
Passed

[asottile]

@sigmavirus24 want to take another pass at this?