What’s happening here is the author is doing outside-in development, but doesn’t want to use mocks or spies to test dependencies that don’t exist. So, when they discover the need for a dependency—which might not be immediately obvious—they stash their work so they’re not bothered by a failing test and half-done code while they implement the dependency.

It’s a technique I use pretty often myself, though not quite as heavily nested as here, and only when I’m genuinely surprised by the need to implement something else before I can make my current test pass.