Fix stdin encoding

[chmp]

Change: Use utf8-encoding when reading files from stdin.

The current code uses stdout.buffer.read() + encode for writing, which implies Utf8 encoding, but uses stdin.read(), which uses an environment specific encoding. See docs.

I ran into this issue when using Mdformat with Helix on Windows. For files with German content and Utf8-encoding the current code mangled any non-ascii characters. The proposed code fixed this behavior.

[chmp]

@hukkin oh. I just executed the command itself - I will fix the test.

[chmp]

I fixed the tests using stdin. Locally, tests using symlinking are failing for me, but that's due to Windows, I guess.

[hukkin]

Thanks for this!

flake8 complains:

tests/test_cli.py:1:1: F401 'io.StringIO' imported but unused
tests/test_config_file.py:1:1: F401 'io.StringIO' imported but unused

Would you able to fix this?

Edit: All good actually. Seems I was able to commit the fix to your branch myself.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (f51432e) to head (449ee57).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #515   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           15        15           
  Lines          970       970           
  Branches       171       171           
=========================================
  Hits           970       970           

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[chmp]

@hukkin Sorry for the late reply. I did not have access to my computer for a couple of days. Thanks a lot for fixing the last issues and merging!