Hands-On Design Patterns and Best Practices with Julia

Performing state verification using stubs

Our goal is to test the open_account function with two scenarios, where the check_background function returns either true or false. When a background check is successful, we expect open_account to return :success. Otherwise, it should return :failure.

Using our terminology, open_account is the function under test, while check_background is the collaborator function. It is a bit unfortunate that we can't really control how the collaborator function behaves. In practice, this function may even reach out to a background check service, the working of which we have little influence on. As a matter of fact, we would not want to call the remote service every single time that we test our software.

Now that ...