2. To better understand the concept of refactoring, find a refactoring in some large, existing system. Build tests that capture the behavior relevant to that part of the system. Refactor, and then check that the tests still pass. You may use the refactoring Guru website I have shared with you. 2. Repair a fault in an existing system. That is, find the code that needs to change and capture the current behavior with tests. At least one of these tests must fail, thus demonstrating that you found the fault. Repair the fault and check that all of your tests now pass