@Test
public void negate() {

  BigInteger result1 = BigIntegerFieldElement.extractValue(element1.negate());
  BigInteger result2 = BigIntegerFieldElement.extractValue(element2.negate());
  BigInteger result3 = BigIntegerFieldElement.extractValue(element3.negate());
  BigInteger value1 = BigIntegerFieldElement.extractValue(element1);
  BigInteger value2 = BigIntegerFieldElement.extractValue(element2);
  BigInteger value3 = BigIntegerFieldElement.extractValue(element3);
  assertThat(result1, Is.is(modulus.getBigInteger().subtract(value1)));
  assertThat(result2, Is.is(modulus.getBigInteger().subtract(value2)));
  assertThat(result3, Is.is(modulus.getBigInteger().subtract(value3)));
}