There should be a Mock mode that provides just the src.rpm with expanded BuildRequires, after successfully iterating the %generate_buildrequires specfile section.
The point is to not perform the whole package build, just %prep and %generate_buildrequires.
This would certainly be useful for implementing the support for dynamic build requires in csmock (without the need to reimplement everything from scratch).
There should be a Mock mode that provides just the src.rpm with expanded BuildRequires, after successfully iterating the %generate_buildrequires specfile section.
The point is to not perform the whole package build, just %prep and %generate_buildrequires.