Mock class and implement custom polling test

[anxolin]

This PR verifies that the child class always have the last word when we are polling, and can signal what should be the result.

It adds 6 new tests for the different outcomes of pollValidate:

The tests were a bit repetitive, so for this one i created a shared function. After all, i just want to test for all case, the poll will respect what the pollValidate says, so i just want to see it handles expectations, and all the result codes.

Note that I had to extend the test order class to be able to override and mock pollValidate (its protected, which makes it harder to mock)

[github-actions]

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