如何为自定义Jackson序列化器编写JUnit-Test？

Suisse 发表于 Dev

瑞士人

我想测试将我的java对象解析为json对象的序列化器。这是我的序列化器类：

public class CountryCodeSerializer extends JsonSerializer<CountryCode> {

    @Override
    public void serialize(CountryCode value, JsonGenerator generator, SerializerProvider provider)
            throws IOException, JsonProcessingException {

        if (value == null) {
            generator.writeString("{}");
        } else {
            generator.writeString(value.toString());
        }
    }

}

我的测试如下所示：

    @Before
        public void setUp() throws Exception {
            stringJson = new StringWriter();
            generator = new JsonFactory().createGenerator(stringJson);
            provider = new ObjectMapper().getSerializerProvider();
            countryCode = CountryCode.parse("us");
        }

        @Test
        public void parsingNullReturnsNull() throws Exception {
            assertThat(countryCodeSerializer.serialize(countryCode, generator, provider)).isEqualTo("{'countrycode':'us'}); //this doesn't work, since serialize() is void

//countryCodeSerializer.serialize(countryCode, generator, provider); //this throws an java.lang.NullPointerException
        }

那么如何测试我的序列化器？我尝试了类似问题的其他答案，但没有任何帮助。

我在其他案例中使用了这样的序列化器：

@JsonSerialize(using = CountryCodeSerializer.class)
    private CountryCode countryCode;

瑞士人

好的，谢谢您的回答。我现在以这种方式得到它，并且工作正常：

我稍微改变了序列化器：

public class CountryCodeSerializer extends JsonSerializer<CountryCode> {
       @Override
        public void serialize(CountryCode value, JsonGenerator generator, SerializerProvider provider)
                throws IOException, JsonProcessingException {

            if (null == value) {
                throw new IllegalArgumentException("CountryCode is null");
            } else {
                generator.writeString(value.toString());
            }
        }        
    }

这是我的两个测试：

public class CountryCodeSerializerTest {

    private CountryCodeSerializer countryCodeSerializer;
    private JsonGenerator jsonGenerator;

    @Before
    public void setUp() throws Exception {
        countryCodeSerializer = new CountryCodeSerializer();
        jsonGenerator = mock(JsonGenerator.class);
    }

    @Test
    public void testNullCountryCodeThrowsIllegalArgumentException() throws Exception {
        try {
            countryCodeSerializer.serialize(null, jsonGenerator, null);
            fail("An IllegalArgumentException should have been thrown.");
        } catch (IllegalArgumentException e) {
            //ok
        }
    }

    @Test
    public void testCountryCodeConvertedToJsonString() throws Exception {
        countryCodeSerializer.serialize(CountryCode.parse("us"), jsonGenerator, null);
        verify(jsonGenerator).writeString("us");
    }
}