As a user of the library, I would like to be able to generate random test images but do so in a deterministic way. I would like to have options from the random.Index(), random.Image(), and random.Layer() functions that allow me to set the rand.Source or the seed to use.

During unit testing I find the random images useful however they are always different (even when I am re-running a test) so it is a larger cognitive load to track what is happening in my test. I cannot add a conditional break-point on the sha256 in one of these images. I do not care what the digest is or what the contents of the images are, I just want them to stay constant unless I change the seed.

The only place a random number generator is used is in Layer() and actually two different random number generators are called. crypto/rand (for the io.Reader interface) and math/rand (for an integer).