### Question:
KeySerialNumber implements Serializable, Loggeable { public String getTransactionCounter () { return transactionCounter; } KeySerialNumber();  KeySerialNumber(String baseKeyID, String deviceID, String transactionCounter); void setBaseKeyID(String baseKeyID); String getBaseKeyID(); void setDeviceID(String deviceID); String getDeviceID(); void setTransactionCounter(String transactionCounter); String getTransactionCounter(); void dump(PrintStream p, String indent);  }### Answer:
@Test public void testGetTransactionCounter() throws Throwable { String result = new KeySerialNumber("testKeySerialNumberBaseKeyID", "testKeySerialNumberDeviceID", "testKeySerialNumberTransactionCounter").getTransactionCounter(); assertEquals("testKeySerialNumberTransactionCounter", result, "result"); }
@Test public void testGetTransactionCounter1() throws Throwable { String result = new KeySerialNumber().getTransactionCounter(); assertNull(result, "result"); }