How can I write a Junit test for a Overide method

Question

How can I write a unit test for an override method? the code looks like this, but I can't get more code covergae for the override method.

public MessageHandler handler() {
    return new MessageHandler() {
        @SneakyThrows
        @Override
        public void handleMessage(Message<?> message) throws MessagingException {
            log.info("Fetching " + message.getPayload());
            var file = (File) message.getPayload();

            var content = Files.readString(Path.of(file.getPath()));

            List<String> fields = Arrays.stream(content.split(";"))
                    .map(String::trim)
                    .collect(Collectors.toList());

            if(((File) message.getPayload()).getName().startsWith("ACH")) {
                log.info("Backup: ", file);
                sftpGetAway.sendToSftpUploaded(file);
            }else {
                log.info("Backup: ", file);
                sftpGetAway.sendToSftpNonUploaded(file);
            }

            processFile(((File) message.getPayload()).getName(), fields);
        }
    };
}

The unit test code is this.

  @Test
public void handler() throws BadRequestException, IOException {
    Message<?> message = MessageBuilder.withPayload("@inboundtest.start()")
            .setHeader("SOME_HEADER_KEY", "SOME_HEADER_VALUE")
            .build();

    MessageHandler hand = Mockito.spy(MessageHandler.class);

    doNothing().when(hand).handleMessage(any(Message.class));
    MessageHandler handler = processAchServiceImp.handler();
    hand.handleMessage(message);
    Assert.assertNotNull(handler);
}

The test runs good but the coverage can't increase.

All the Override handleMessage method and I want to cover those lines — Abraham Macias, Oct 09 '21 at 03:56
You’ve stubbed the method to do nothing in your test, so the original code won’t be called. — Tim Moore, Oct 09 '21 at 04:05
After `MessageHandler handler = processAchServiceImp.handler();` you have the `MessageHandler` instance that you probably want to test. Now you need to test it by calling `handler.handleMessage(...)` and verify the outcome. — Thomas Kläger, Oct 09 '21 at 05:34
@ThomasKläger thanks that was ecactly that I need, It works . And thanks to all of you — Abraham Macias, Oct 11 '21 at 14:28

score 0 · Answer 1 · answered Oct 09 '21 at 04:09

Seems like you are mocking the class undertest :

MessageHandler hand = Mockito.spy(MessageHandler.class);
doNothing().when(hand).handleMessage(any(Message.class));

You should mock your dependcies instead. This link should give more explaination about your issue.

How can I write a Junit test for a Overide method

1 Answers1