Which tests are usefull?

Hello,
I want to use tests with Oxid.
So far I have seen the testing library and it looks like there are two kind of tests. Existing tests and writing tests for my own modules.

I have seen tests are here:

  • oxideshop/vendor/oxid-esales/testing-library/tests
  • oxideshop/vendor/oxid-esales/oxideshop-ce/tests
  • oxideshop/vendor/oxid-esales/oxideshop-pe/Tests

and here:

  • oxideshop/source/modules/bestit/amazonpay4oxid/tests

Which tests are usefull to execute?

I have tried with ./vendor/bin/runtests and configuration in test_config.yml

At the moment I got an error:
OXID Logger.ERROR: Unknown column ‘oxserial’ in ‘field list’

What is the recomended way to use tests?