You have new functionality to be tested and also you have a bug fix that needs to be tested. How do you go about testing each of these?

As testing a new functionality needs some time as we need to write the test cases of that as well where as testing an existing bug is just a regression testing so if there is a release then I would prefer to test the bug first.
And if he says that explain the process then explain the test scenario creation test case creation and the entire process for new functionality and for bug testing explain regression testing process