RestTemplate模拟抛出NullPointerException [英] RestTemplate Mock throws NullPointerException

问题描述

我有一个rest模板，可以在服务类中的方法中进行调用，如下所示:

I have a rest template that makes a call in a method in a service class like so:

public CustomerResponse someMethod() {
CustomerResponse response = restTemplate.exchange(url, HttpMethod.GET, null,  CustomerRes.class).getBody();
return response;
}

尝试在测试类中模拟restTemplate时，它会在调用模拟restTemplate的行上不断抛出NullPointerException:

When trying to mock the restTemplate in my test class, it keeps throwing a NullPointerException on the line where the mock restTemplate is called:

public void checkResponseIsNotNull() {
CustomerResponse customerResponseMock = mock(CustomerResponse.class);
when(restTemplate.exchange(url, HttpMethod.GET, null, CustomerResponse.class).getBody()).thenReturn(customerResponseMock);
CustomerResponse cr = service.someMethod();
Assert.assertNotNull(cr);
}

为什么会抛出NullPointer?我之前已经嘲笑过RestTemplate，只是没有getBody()方法，这导致人们相信它会导致空指针.

Why is NullPointer being thrown? I have mocked a RestTemplate before, just without the getBody() method which leads be to believe its that which is causing the null pointer.

推荐答案

您应该再添加一个模拟级别:

You should add one more level of mocking:

CustomerResponse customerResponseMock = mock(CustomerResponse.class);
ResponseEntity reMock = mock(ResponseEntity.class);

when(reMock.getBody()).thenReturn(customerResponseMock);
when(restTemplate.exchange(url, HttpMethod.GET, null, CustomerResponse.class)).thenReturn(reMock);

CustomerResponse cr = service.someMethod();

最初，您只设置了ResponseEntity，而RestTemplate仍保留默认设置..因此，在调用exchange时返回null.

Originally you were setting-up the ResponseEntity only and the RestTemplate still remained with the defaults.. thus returning null when exchange has been called.

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