### Question:
Ed25519FieldElement implements Serializable { public Ed25519FieldElement invert() { Ed25519FieldElement f0; Ed25519FieldElement f1; f0 = this.square(); f1 = this.pow2to9(); f0 = f0.multiply(f1); f1 = this.pow2to252sub4(); for (int i = 1; i < 4; ++i) { f1 = f1.square(); } return f1.multiply(f0); } Ed25519FieldElement(final int[] values); static Ed25519FieldElement sqrt(final Ed25519FieldElement u, final Ed25519FieldElement v); int[] getRaw(); boolean isNonZero(); Ed25519FieldElement add(final Ed25519FieldElement g); Ed25519FieldElement subtract(final Ed25519FieldElement g); Ed25519FieldElement negate(); Ed25519FieldElement multiply(final Ed25519FieldElement g); Ed25519FieldElement square(); Ed25519FieldElement squareAndDouble(); Ed25519FieldElement invert(); Ed25519EncodedFieldElement encode(); boolean isNegative(); @Override int hashCode(); @Override boolean equals(final Object obj); @Override String toString();  }### Answer:
@Test public void invertReturnsCorrectResult() { for (int i = 0; i < 1000; i++) { final Ed25519FieldElement f1 = MathUtils.getRandomFieldElement(); final BigInteger b1 = MathUtils.toBigInteger(f1); final Ed25519FieldElement f2 = f1.invert(); assertEquals(f2, b1.modInverse(Ed25519Field.P)); } }