for (long x : ALL_LONG_CANDIDATES) {
      for (long m : NEGATIVE_LONG_CANDIDATES) {
        assertThrows(ArithmeticException.class, () -> LongMath.mod(x, m));
      }
    }
  }

  public void testGCDExhaustive() {
    for (long a : POSITIVE_LONG_CANDIDATES) {
      for (long b : POSITIVE_LONG_CANDIDATES) {
        assertEquals(valueOf(a).gcd(valueOf(b)), valueOf(LongMath.gcd(a, b)));
      }
    }
  }