test PL examples

[Borda]

What does this PR do?

these tests have been not tested even we have written tests for them...

Before submitting

• Was this discussed/approved via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure your PR does only one thing, instead of bundling different changes together? Otherwise, we ask you to create a separate PR for every change.
• Did you make sure to update the documentation with your changes?
• Did you write any new necessary tests?
• Did you verify new and existing tests pass locally with your changes?
• If you made a notable change (that affects users), did you update the CHANGELOG?

PR review

Anyone in the community is free to review the PR once the tests have passed.
Before you start reviewing make sure you have read Review guidelines. In in short, see following bullet-list:

• Is this pull request ready for review? (if not, please submit in draft mode)
• Check that all items from Before submitting are resolved
• Make sure the title is self explanatory and the description concisely explains the PR
• Add labels and milestones (and optionally projects) to the PR so it can be classified; Bugfixes should be including in bug-fix release milestones (m.f.X) and features should be included in (m.X.b) releases.

Did you have fun?

Make sure you had fun coding 🙃

[tchaton]

Great PR !

[codecov]

Codecov Report

Merging #4551 (052c6a6) into master (b8a1916) will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #4551   +/-   ##
======================================
  Coverage      93%     93%           
======================================
  Files         117     117           
  Lines        8937    8937           
======================================
  Hits         8304    8304           
  Misses        633     633           

[Borda]

the founding yield in #4694