https://github.com/thoughtbot/shoulda-matchers/issues/1067
This issue led to the failure of the solution I implemented before in 8f88362264.
Because of it shoulda-matchers will just ignore the given record for the
validation check and just take the first existing one which in this case
can still contain a only-digits code, because it was generated in the
before-block.
Because in some ocassions a tournament code with only digits is
generated which would fail this test because shoulda is not able to
convert it to an uppercase version to test for case-sensitivity of the
validation.
Thor77