如何使用Jackson获得JsonProcessingException [英] How to get a JsonProcessingException using Jackson

问题描述

可能是一个奇怪的问题，但确实我想在测试中获得更多的覆盖范围，尽管我针对JsonProcessingException进行了编码，但我无法创建产生此异常的有效负载，也许是因为杰克逊非常聪明并且将所有内容都转换为字符串，甚至对于错误的字符串也都遵循JSON规范.我的问题是杰克逊相当出色:)

Might be a strange question but indeed I would like to achieve a a bit more coverage on my tests and although I coded against a JsonProcessingException I can't create a payload that generates this exception, maybe because Jackson is quite smart and converts everything to a string, and even for bad strings it goes around the JSON specs. My problem is that Jackson is quite good :)

我基本上想要一个有效负载，当我运行此负载时，它会与JsonProcessingException断开:

I basically want a payload that when I run this, it break with JsonProcessingException:

String jsonPayload = objectMapper.writeValueAsString(payload);

我尝试过类似的事情:

HashMap<String, String> invalidJSONPayload= new HashMap<>();

invalidJSONPayload.put("021",021);
invalidJSONPayload.put("---",021);
invalidJSONPayload.put("~",021);

我对这种类型不感到困惑，所以随时建议另一个.例如，一个空对象会抛出JsonMappingException，而我也已经捕获了该对象.

I'm not fussed with the type, so feel free to suggest another one. An empty object for example, throws JsonMappingException and I already catch that one as well.

推荐答案

我想做同样的事情，并最终通过使用Mockito的间谍"函数完成了该任务，该函数将真实对象与模拟对象包装在一起.对模拟对象的所有调用都会转发到真实对象，但您尝试模拟的对象除外.例如:

I wanted to do the same thing, and eventually accomplished it by using the Mockito "spy" function, which wraps a real object with a mock object. All calls to the mock object get forwarded to the real object, except those you are trying to mock. For example:

ObjectMapper om = Mockito.spy(new ObjectMapper());
Mockito.when( om.writeValueAsString(ErrorObject.class)).thenThrow(new JsonProcessingException("") {});

om的所有用法将由基础ObjectMapper实例处理，直到传入ErrorObject的实例为止，这时将抛出JsonProcessingException.

All usages of om will be handled by the underlying ObjectMapper instance until an instance of ErrorObject gets passed in, at which point the JsonProcessingException will be thrown.

新的JsonProcessingException被创建为匿名类，因为它是受保护的类，并且只能实例化子类.

The newJsonProcessingException is created as an anonymous class, as it is a protected class and only a sub-class can be instantiated.

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