assertThrows(IllegalArgumentException.class, () -> IntMath.gcd(a, 3));
      assertThrows(IllegalArgumentException.class, () -> IntMath.gcd(3, a));
    }
  }

  public void testGCDNegativeZeroThrows() {
    for (int a : NEGATIVE_INTEGER_CANDIDATES) {
      assertThrows(IllegalArgumentException.class, () -> IntMath.gcd(a, 0));
      assertThrows(IllegalArgumentException.class, () -> IntMath.gcd(0, a));
    }