测试自定义Jackson序列化器不起作用

Question

我有一个自定义序列化程序，可以为我序列化LocalDateTime。

    public class LocalDateTimeJsonSerializer extends JsonSerializer<LocalDateTime> {

        private static final DateTimeFormatter FORMATTER = DateTimeFormatter.ISO_LOCAL_DATE_TIME;

        @Override
        public void serialize(LocalDateTime date, JsonGenerator generator, SerializerProvider arg2) throws IOException, JsonProcessingException {
            final String dateString = date.format(FORMATTER);
            generator.writeString(dateString);
        }
    }

我的问题是我的测试无法正常工作，就像我的jsonGenerator在序列化后仍然为空

  @Test
        public void serialises_LocalDateTime() throws JsonProcessingException, IOException {
            Writer jsonWriter = new StringWriter();
            JsonGenerator jsonGenerator = new JsonFactory().createGenerator(jsonWriter);
            SerializerProvider serializerProvider = new ObjectMapper().getSerializerProvider();
            LocalDateTimeJsonSerializer  ldt = new LocalDateTimeJsonSerializer();
            ldt.serialize(LocalDateTime.of(2000, Month.JANUARY, 1, 0, 0), jsonGenerator, serializerProvider);
            jsonGenerator.flush();
            //assertEquals(jsonWriter.toString(), "2000-01-01T00:00:00");
        }

..任何想法？