| com.reeltwo.jumble.mutation |
Mutation tester to work in conjunction with JUnit.
What does a "T" output mean?
The mutation caused the unit tests to take longer than expected
(possibly having put the code into an infinite loop). Jumble gives
the coder the benefit of the doubt in such situations.
Can Jumble ever incorrectly report an arithmetic problem?
Yes. Certain combinations of operations and constants give the same
result for different examples. For example,
y = x * sign;
y = x / sign;
give the same result for sign = +1 or sign = -1.
Can Jumble ever incorrectly report a conditional problem?
Yes. Certain pieces of code can be modified without invalidating the
code. One example of this is where a condition is used to select
different code for performance reasons rather than correctness.
Suppose f1(x) and f2(x) compute the same function but are exhibit
different performance depending on x. Valid code might then be
int foo(int x) {
return x < 10 ? f1(x) : f2(x);
}
mutating the condition x < 10 would not change the correctness of the
code only the speed. Unless there is a very sensitive speed test this
modification is likely to pass unit tests.
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