FactorialDigitSum { protected static BigInteger bigInteger(int number) { return bigInteger(String.valueOf(number)); }  static BigInteger factorialOf(int number); static BigInteger sumOfDigits(BigInteger number); static BigInteger sumOfFactorialDigits(int number);  }
@Test public void factorial_of_zero_is_1() { factorialAssertion(0, FactorialDigitSum.bigInteger(1)); }
@Test public void factorial_of_1_is_1() { factorialAssertion(1, FactorialDigitSum.bigInteger(1)); }
@Test public void factorial_of_2_is_2() { factorialAssertion(2, FactorialDigitSum.bigInteger(2)); }
@Test public void factorial_of_10_is_3628800() { factorialAssertion(10, FactorialDigitSum.bigInteger(3628800)); }
@Test public void factorial_of_100_is_3628800() { factorialAssertion(100, FactorialDigitSum.bigInteger("93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000")); }