Comment by j1mr10rd4n

There's another good reason that hasn't been detailed in the comments so far: expressing intent.

A test should communicate its reason for testing the subject, and when an input is generated or random, it clearly communicates that this test doesn't care about the specific _value_ of that input, it's focussed on something else.

This has other beneficial effects on test suites, especially as they change over the lifetime of their subjects:

* keeping test data isolated, avoiding coupling across tests * avoiding magic strings * and as mentioned in this thread, any "flakiness" is probably a signal of an edge-case that should be handled deterministically and * it's more fun [1]

[1] https://arxiv.org/pdf/2312.01680