	@Test
	public void testUnknownTransactionType() throws Exception {

		final Map<String, String> nvp = new HashMap<String, String>();
		
		nvp.put("txn_type", "unknown");
		parser = new IPNMessageParser(nvp, true);
		
		final IPNMessage message = parser.parse();
		
		assertThat(message.getTransactionType(), nullValue());
	}