The new Sandbox Post Copy tasks are a great addition and I'm eager to try them but until the release to Production starts on Feb. 6, it seems impossible to experiment with the behavior. I reconstructed the sample in a sandbox and while I can get the unit test to pass, I can't figure out a way to invoke the code so that it returns the sandbox's ID and Name. The sample code requires passing the values to the class the implements SandboxPostCopy but my interpretation of the feature is that when it's invoked post-copy, those values in SandboxContext will be derived from the new sandbox itself.
My intention is to run a Lead/Contact email address sanitizer that will imbed the real email address in an email address that we control (e.g. firstname.lastname@example.org) so we can safely enable Email Deliverability and monitor all outbound emails as well as tell both the contact email and sandbox from which they came, so getting the sandboxName value is necessary.