### Question:
ApduResponse implements Serializable { @Override public String toString() { String prefix; if (isSuccessful()) { prefix = "ApduResponse: SUCCESS, RAWDATA = "; } else { prefix = "ApduResponse: FAILURE, RAWDATA = "; } return prefix + ByteArrayUtils.toHex(this.bytes); } ApduResponse(byte[] buffer, Set<Integer> successfulStatusCodes); boolean isSuccessful(); int getStatusCode(); byte[] getBytes(); byte[] getDataOut(); @Override String toString(); @Override boolean equals(Object o); @Override int hashCode();  }### Answer:
@Test public void testToStringNull() { ApduResponse resp = new ApduResponse(null, null); assertNotNull(resp.toString()); }