Use bit better mocks of AbstractProcessor

[pavoljuhas]

Tell create_autospec to produce an instance-like mock.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.62%. Comparing base (912a76e) to head (23a6771).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7909      +/-   ##
==========================================
- Coverage   99.62%   99.62%   -0.01%     
==========================================
  Files        1104     1104              
  Lines       99317    99317              
==========================================
- Hits        98944    98943       -1     
- Misses        373      374       +1     

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