Random rand = new Random(1);
    for (int bits = 10; bits < 63; bits++) {
      for (int i = 0; i < 2000; i++) {
        // A random long between 0 and Long.MAX_VALUE, inclusive.
        long l = rand.nextLong() & ((1L << bits) - 1);
        assertEquals(BigInteger.valueOf(l).isProbablePrime(100), LongMath.isPrime(l));
      }
    }
  }

  @GwtIncompatible // isPrime is GWT-incompatible

    Random rand = new Random(1);
    for (int bits = 10; bits < 63; bits++) {
      for (int i = 0; i < 2000; i++) {
        // A random long between 0 and Long.MAX_VALUE, inclusive.
        long l = rand.nextLong() & ((1L << bits) - 1);
        assertEquals(BigInteger.valueOf(l).isProbablePrime(100), LongMath.isPrime(l));
      }
    }
  }

  @GwtIncompatible // isPrime is GWT-incompatible

  }

  public void testByteArrayRoundTrips() {
    Random r = new Random(5);
    byte[] b = new byte[Longs.BYTES];

    for (int i = 0; i < 1000; i++) {
      long num = r.nextLong();
      assertThat(Longs.fromByteArray(Longs.toByteArray(num))).isEqualTo(num);

      r.nextBytes(b);
      long value = Longs.fromByteArray(b);

  }

  public void testByteArrayRoundTrips() {
    Random r = new Random(5);
    byte[] b = new byte[Longs.BYTES];

    for (int i = 0; i < 1000; i++) {
      long num = r.nextLong();
      assertThat(Longs.fromByteArray(Longs.toByteArray(num))).isEqualTo(num);

      r.nextBytes(b);
      long value = Longs.fromByteArray(b);