Why can't I mock Math using JMockit

Question

I am running into a problem mocking out java.lang.Math using JMockit (1.21). See below for a simplified use of my actual class. Basically somewhere in my code I use

Answer 1

Because 1) methods from java.lang.Math (in particular, Math.min(a, b)) get called all the time by other classes from the JRE (for example, look inside java.lang.String), and 2) when JMockit mocks a class (with @Mocked, anyway), it gets mocked for the duration of the test, regardless of where the calls are coming from.

Bottom line, don't mock low-level JRE classes unless you really know what you are doing. In this particular case, JMockit should probably deny the full mocking of java.lang.Math, as really there is no good reason (that I can see) for doing it.