refactor: add test on sponsor

[baby230211]

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• Bugfix
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[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.90 🎉

Comparison is base (411b8b5) 69.49% compared to head (77c8443) 70.39%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master       #3      +/-   ##
==========================================
+ Coverage   69.49%   70.39%   +0.90%     
==========================================
  Files          82       85       +3     
  Lines        3357     3378      +21     
==========================================
+ Hits         2333     2378      +45     
+ Misses       1024     1000      -24     

Impacted Files	Coverage Δ
src/proposals/forms/mixins.py	100.00% <ø> (ø)
src/proposals/forms/proposals.py	100.00% <ø> (ø)
src/pycontw2016/urls.py	85.71% <ø> (ø)
src/core/choices.py	100.00% <100.00%> (ø)
src/core/models.py	95.71% <100.00%> (-0.44%)	⬇️
src/proposals/api/urls.py	100.00% <100.00%> (ø)
src/proposals/api/views.py	100.00% <100.00%> (ø)

... and 4 files with indirect coverage changes

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