To clarify my post: I see the reason for Firecracker to exist in general, it's great. But does "e2e tests" include untrusted code? I think it really shouldn't.

So why use firecracker here? Invoking your tests in a bare VM or container is great for making sure that you are controlling the environment and enumerating your system dependencies. But this post proposes discarding those things and instead using some saved state as the entry point into your Firecracker. So now you are booting from Your Image instead of a { Official Distro Image + Dependency Recipe }. It seems like a step backward.