It varies by case. For the particular example of time, some common approaches are to hook the sys call for time such that it returns a constant value, or to te

It varies by case. For the particular example of time, some common approaches are to hook the sys call for time such that it returns a constant value, or to teach your tool to output a constant value. The Nix thesis (https://nixos.org/~eelco/pubs/phd-thesis.pdf https://nixos.org/~eelco/pubs/phd-thesis.pdf) is a great read and goes through a bunch of these examples as part of its research.