A problem with test case reduction occurs when your test generator also ensures the test input satisfies some properties. This means naive reduction can produc

A problem with test case reduction occurs when your test generator also ensures the test input satisfies some properties. This means naive reduction can produce invalid inputs for which "failure" doesn't represent a bug. An example is in testing C compilers where the C code must not exhibit any of the many undefined behaviors described in the C standard. Creduce goes to some lengths to work around this problem. A solution to this is doing the reduction on a tree of random numbers provided to the test generator, so the output is always a legitimate test input. The Hypothesis testing system takes this approach.