Alicia recently moved to a new country and took a job with a small company willing to pay well and help with relocation costs. Overall, the code base was pretty solid. Despite the overall strong code base, one recurring complaint was that running the test suite was painfully long.

While Alicia doesn't specify what the core business is, but says: "in this company's core business, random numbers were the base of everything."

As such, they did take generating random numbers fairly seriously, and mostly used strong tools for doing that. However, whoever wrote their test suite was maybe a bit less concerned, and wrote this function:

public static Long generateRandomNumberOf(int length) {
    while (true) {
            long numb = (long)(Math.random() * 100000000 * 1000000); // had to use this as int's are to small for a 13 digit number.
            if (String.valueOf(numb).length() == length)
                return numb;		
        }		
}

They want many digits of random number. So they generate a random floating point, and then multiply it a few times to get a large number. If the length of the resulting number, in characters, is the desired length, we return it. Otherwise, we try again.

The joy here, of course, is that this function is never guaranteed to exit. In fact, if you request more than 15 digits, it definitely won't exit. In practice, most of the time, the function is able to hit the target length in a relative handful of iterations, but there's no guarantee for that.

Alicia was tracking down a bug in a test which called this function. So she went ahead and fixed this function so that it use a sane way to generate the appropriate amount of entropy that actually guaranteed a result. She included that change in her pull request, nobody had any comments, and it got merged in.

The unit tests aren't vastly faster than they were, but they are faster. Who knows what other surprises the test suite has in store?

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