add test helper

[arnaudbore]

No description provided.

[codecov-commenter]

Codecov Report

Merging #220 (bd392d5) into master (8ab482e) will increase coverage by 1.72%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #220      +/-   ##
==========================================
+ Coverage   78.05%   79.78%   +1.72%     
==========================================
  Files          15       15              
  Lines         925      925              
  Branches      180      180              
==========================================
+ Hits          722      738      +16     
+ Misses        167      148      -19     
- Partials       36       39       +3     

Flag	Coverage Δ
pytest	79.78% <ø> (+1.72%)	⬆️

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see 2 files with indirect coverage changes