Remove unused package private method and tests

[snuyanzin]

Since now tests able to read data from file to construct expected set we don't need to call tests thousand number of times

[codecov-commenter]

Codecov Report

Merging #772 (ef39f47) into main (8cbb8b9) will decrease coverage by 0.06%.
The diff coverage is n/a.

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@@             Coverage Diff              @@
##               main     #772      +/-   ##
============================================
- Coverage     92.86%   92.81%   -0.06%     
+ Complexity     2633     2632       -1     
============================================
  Files           284      284              
  Lines          5202     5202              
  Branches        537      537              
============================================
- Hits           4831     4828       -3     
- Misses          243      245       +2     
- Partials        128      129       +1     

see 3 files with indirect coverage changes

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[kingthorin]

Thanks