Beautiful Testing

Chapter 10. Testing a Random Number Generator

John D. Cook

According to the classical definition of beauty, something is beautiful if it exhibits both complexity and unity. Professor Gene Veith explained this idea in an editorial by describing two kind of paintings:^[51]

In painting a black canvas has unity, but it has no complexity. A canvas of random paint splatterings has complexity, but it has no unity.

Michelangelo’s painting of the Sistine Chapel ceiling has rich detail along with order and balance. It exhibits complexity and unity. It is beautiful.

Some works of beauty are easy to appreciate because both the complexity and the unity are apparent. I would say the Sistine Chapel falls in this category. However, other works require more education to appreciate because it takes knowledge and skill to see either the complexity or the unity. Modern jazz may fall into this latter category. The complexity is obvious, but the unity may not be apparent to untrained ears. Tests for random number generators may be more like modern jazz than the Sistine Chapel; the complexity is easier to see than the unity. But with some introduction, the unity can be appreciated.

What Makes Random Number Generators Subtle to Test?

Software random number generators are technically pseudorandom number generators because the output of a deterministic program cannot really be random. We will leave the “pseudo” qualification understood and simply speak of random number generators (RNGs). Even though the output ...