How can i faild a test in junit?

I want to test some simple programs with evosuite in intellij and I want some test be failed . I was generated test with evosuite and test_cases are built. But when i test them with junit after, all of them are passed ! How can i faile some test in program? This is my simple program that I add "while(true)" to be wrong:

While(true) int a =8; int b=2; a=b;