Written by Jamie Tanna
on 
CC-BY-NC-SA-4.0 Apache-2.0
1 mins

Validating a MockMvc Response Has No Content Type

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If you're writing tests to validate i.e. that an HTTP 406 is returned from your API when failing to negotiate, you should validate that the content-type of the response is not set.

In Spring (Boot), this may be achieved using a MockMvc test, like so:

import static org.assertj.core.api.Assertions.assertThat;
import static org.hamcrest.Matchers.matchesRegex;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.web.servlet.MockMvc;

@SpringBootTest
@AutoConfigureMockMvc
class NegotiationIntegrationTest {

  @Autowired private MockMvc mockMvc;

  @Test
  void notAcceptableStatusIsReturnedIfNegotiationFails() throws Exception {
    mockMvc
        .perform(get("/endpoint").accept("in/valid").header("correlation-id", "not-valid"))
        .andExpect(status().isNotAcceptable())
        .andExpect(content().string("")) // empty response
        .andExpect(header().doesNotExist("content-type"));
  }

Or we can create a custom ResultMatcher and validate a little more:

import static org.assertj.core.api.Assertions.assertThat;
import static org.hamcrest.Matchers.matchesRegex;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.web.servlet.MockMvc;

  @Test
  void notAcceptableStatusIsReturnedIfNegotiationFails() throws Exception {
    mockMvc
        .perform(get("/endpoint").accept("in/valid").header("correlation-id", "not-valid"))
        .andExpect(status().isNotAcceptable())
        .andExpect(
            result -> {
              assertThat(result.getResponse().getContentType()).isNull();
              assertThat(result.getResponse().getContentLength()).isZero();
              assertThat(result.getResponse().getContentAsString()).isEmpty();
            });
  }

We need to do this because the content().contentType() call does not allows us to provide a null value.

Written by Jamie Tanna's profile image Jamie Tanna on , and last updated on .

Content for this article is shared under the terms of the Creative Commons Attribution Non Commercial Share Alike 4.0 International, and code is shared under the Apache License 2.0.

#blogumentation #spring #spring-boot #testing.

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