RestTemplate模拟抛出NullPointerException

Question

我有一个rest模板，可以在服务类中的方法中进行如下调用：

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：

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。

Answer 1

您应该再添加一个模拟级别：

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，您仅设置了ResponseEntity，而RestTemplate仍然保留默认设置。因此，在调用exchange时返回null。