@Override
    public String buildContext() {
        final String selector = ((Collection<?>) getSource())
                .stream()
                .map(s -> ((SelectorDO) s).getName())
                .collect(Collectors.joining(","));
        return String.format("the selector[%s] is %s", selector, StringUtils.lowerCase(getType().getType().toString()));
    }
@Test
    void buildContext() {
        String expectMsg = String.format("the selector[%s] is %s", selectorDO.getName(), StringUtils.lowerCase(batchSelectorDeletedEvent.getType().getType().toString()));

        String actualMsg = batchSelectorDeletedEvent.buildContext();

        assertEquals(expectMsg, actualMsg);
    }