Random rand = new Random(1);
    for (int bits = 10; bits < 63; bits++) {
      for (int i = 0; i < 100; i++) {
        long p = BigInteger.probablePrime(bits, rand).longValue();
        assertTrue(LongMath.isPrime(p));
      }
    }
  }

  @GwtIncompatible // isPrime is GWT-incompatible
  public void testIsPrimeOnRandomComposites() {
    Random rand = new Random(1);

    Random rand = new Random(0);
    int keyBits = 32;
    int hashBits = function.bits();
    for (int i = 0; i < keyBits; i++) {
      int[] same = new int[hashBits];
      int[] diff = new int[hashBits];
      // go through trials to compute probability
      for (int j = 0; j < trials; j++) {
        int key1 = rand.nextInt();
        // flip input bit for key2

    assertTrue(len4.matches('d'));
    for (char c = 'e'; c < 'z'; c++) {
      assertFalse(len4.matches(c));
    }

    Random rand = new Random(1234);
    for (int testCase = 0; testCase < 100; testCase++) {
      char[] chars = randomChars(rand, rand.nextInt(63) + 1);
      CharMatcher m = SmallCharMatcher.from(bitSet(chars), new String(chars));
      checkExactMatches(m, chars);
    }
  }

    assertTrue(len4.matches('d'));
    for (char c = 'e'; c < 'z'; c++) {
      assertFalse(len4.matches(c));
    }

    Random rand = new Random(1234);
    for (int testCase = 0; testCase < 100; testCase++) {
      char[] chars = randomChars(rand, rand.nextInt(63) + 1);
      CharMatcher m = SmallCharMatcher.from(bitSet(chars), new String(chars));
      checkExactMatches(m, chars);
    }
  }

    for (int i = 0; i < 100000; i++) {
      assertEquals(LongMath.isPrime(i), IntMath.isPrime(i));
    }

    // Then check 1000 deterministic pseudo-random int values.
    Random rand = new Random(1);
    for (int i = 0; i < 1000; i++) {
      int n = rand.nextInt(Integer.MAX_VALUE);
      assertEquals(LongMath.isPrime(n), IntMath.isPrime(n));
    }
  }

  public void testSaturatedAbs() {