### Question:
MersennePrimeFieldElement implements FieldElement { @Override public String toString() { return "MersennePrimeFieldElement{" + "value=" + value + ", modulus =" + modulus + '}'; } private  MersennePrimeFieldElement(BigInteger value, MersennePrimeModulus modulus); @Override FieldElement add(FieldElement operand); @Override FieldElement subtract(FieldElement operand); @Override FieldElement negate(); @Override FieldElement multiply(FieldElement operand); @Override FieldElement sqrt(); @Override FieldElement modInverse(); @Override String toString();  }### Answer:
@Test public void toStringTest() { FieldElement element = MersennePrimeFieldElement.create(BigInteger.valueOf(7854), bigModulus); assertThat(element.toString(), StringContains.containsString("7854")); }