Fix and re-add subscription test

[paologalligit]

Description

This PR reintroduce the pending subscription test previously deleted because flaky.

Fixes # issue-214

Type of change

• Add new test

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules
• I have not added any vulnerable dependencies to my code

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 62.70%. Comparing base (27e60e6) to head (706858b).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #763      +/-   ##
==========================================
+ Coverage   62.59%   62.70%   +0.10%     
==========================================
  Files         199      199              
  Lines       18093    18093              
==========================================
+ Hits        11326    11345      +19     
+ Misses       5685     5664      -21     
- Partials     1082     1084       +2     

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