subethamail - a simple way to test mail sender

Problem

為了要驗證程式所寄出的人或訊息是否正確，我們可以寫一些mock程式去攔截收到的內容；也可以透過java mail去接收者的信箱中把內容撈出來比對。這些方法寫起來會比較花時間，如果能透過既有的mail server，可能就會容易多了。

How to?

原先Albert有找到一套叫FakeSMTP的library，經過試驗發現它並不容易被拿進來寫UnitTest。因此直接使用它所相依的library subethamail，非常簡單就可以讓你去確認寄送者、接收者與信件內容:

	private SMTPServer server;
	private List<String> toList = new ArrayList<>();
	private String testContent;
 
	@Before
	public void setUp() throws Exception {
		try {
			server = new SMTPServer(new SimpleMessageListenerAdapter(new SimpleMessageListener() {
 
				@Override
				public void deliver(String from, String to, InputStream content)
						throws TooMuchDataException, IOException {
					logger.info("deliver {}", from);
					logger.info("deliver {}", to);
					toList.add(to);
					testContent = IOUtils.toString(content);
				}
 
				@Override
				public boolean accept(String from, String to) {
					logger.info("accept {}", from);
					logger.info("accept {}", to);
					return true;
				}
			}));
			server.setBindAddress(InetAddress.getByName("0.0.0.0"));
			server.setPort(25);
 
			server.start();
			System.out.println("Start SMTP Server");
		} catch (Exception e) {
			// Ignore
		}
 
	}
 
	@After
	public void tearDown() throws Exception {
		if (server !=null)
			server.stop();
	}
 
	@Test
	public void test() {
		// do something
 
		assertEquals(2, toList.size());
		assertTrue(toList.contains("test1@tonylin.org.tw"));
		assertTrue(toList.contains("test2@tonylin.org.tw"));
		assertTrue(testContent.contains("test message"));
	}

Reference

• subethasmtp
• FakeSMTP