### Question:
Ed25519EncodedFieldElement implements Serializable { public boolean isNonZero() { return 0 == ArrayUtils.isEqualConstantTime(this.values, this.zero); } Ed25519EncodedFieldElement(final byte[] values); byte[] getRaw(); boolean isNegative(); boolean isNonZero(); Ed25519FieldElement decode(); Ed25519EncodedFieldElement modQ(); Ed25519EncodedFieldElement multiplyAndAddModQ(
      final Ed25519EncodedFieldElement b, final Ed25519EncodedFieldElement c); @Override int hashCode(); @Override boolean equals(final Object obj); @Override String toString();  }### Answer:
@Test public void isNonZeroReturnsFalseIfEncodedFieldElementIsZero() { final Ed25519EncodedFieldElement encoded = new Ed25519EncodedFieldElement(new byte[32]); MatcherAssert.assertThat(encoded.isNonZero(), IsEqual.equalTo(false)); }
@Test public void isNonZeroReturnsTrueIfEncodedFieldElementIsNonZero() { final byte[] values = new byte[32]; values[0] = 5; final Ed25519EncodedFieldElement encoded = new Ed25519EncodedFieldElement(values); MatcherAssert.assertThat(encoded.isNonZero(), IsEqual.equalTo(true)); }