Add tests on recursive calls

[ddeclerck]

Tests taken out of PR 110. This has yet to be investigated further.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 65.88%. Comparing base (89c45a3) to head (331964a).

:exclamation: Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@                  Coverage Diff                  @@
##           gcos4gnucobol-3.x     #139      +/-   ##
=====================================================
+ Coverage              65.87%   65.88%   +0.01%     
=====================================================
  Files                     32       32              
  Lines                  59483    59483              
  Branches               15709    15709              
=====================================================
+ Hits                   39182    39189       +7     
+ Misses                 14282    14277       -5     
+ Partials                6019     6017       -2     

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.