Came up with a couple more use cases for new code.

• Configuration sanity check - ensure that directories exist, numeric values are within bounds, sane defaults have been substituted etc after the configuration has been loaded.
• Output sanity check - ensure that links point back to the app, all needed IDs are present, credit card details are censored etc. In particular, e-mail templates have been notoriously hard to test in almost every of my workplaces.

Of course there are multiple ways to do that, Assert::Refute just provides a convenient language for both specification and report.