> Thanks for the explanation. It makes sense that we start with a given > seed and then each iteration is different because it re-uses the same > Random instance (or whatever static state?) without re-initialization? >
It doesn't reuse the same random instance - it's not that simple - it hierarchically forks the random seed between tests, classes, reiterations etc., and then initializes the context's random so that runs are predictable and repeatable even if you run a subset of tests for the given main seed. Random instances are also not reused between threads in an attempt to make failures reproducible (this, of course, is not fool-proof). If you care to look, there are more documented examples with somewhat increasing complexity here: https://github.com/randomizedtesting/randomizedtesting/tree/master/examples/maven/src/main/java/com/carrotsearch/examples/randomizedrunner In particular, these talk about hierarchical seed propagation: https://github.com/randomizedtesting/randomizedtesting/blob/master/examples/maven/src/main/java/com/carrotsearch/examples/randomizedrunner/Test004MoreRandomness.java https://github.com/randomizedtesting/randomizedtesting/blob/master/examples/maven/src/main/java/com/carrotsearch/examples/randomizedrunner/Test006RepeatingTests.java D.
