How to extract value from JSON response when using Spring MockMVC

You can simply use JsonPath.read on the result object:

MvcResult result = mockMvc.perform(post("/api/tracker/jobs/work")    .contentType(TestUtil.APPLICATION_JSON_UTF8)    .content(TestUtil.convertObjectToJsonBytes(workRequest)))    .andExpect(status().isCreated())    .andReturn();    String id = JsonPath.read(result.getResponse().getContentAsString(), "$.id")Work work = workService.findWorkById(id);...

I have managed to solve my problem using Spring MockMVC result handler. I created a testing utility to convert the JSON string back to an object and so allowing me to get the ID.

Conversion Utility:

 public static <T>  Object convertJSONStringToObject(String json, Class<T> objectClass) throws IOException {    ObjectMapper mapper = new ObjectMapper();    mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);    JavaTimeModule module = new JavaTimeModule();    mapper.registerModule(module);    return mapper.readValue(json, objectClass);}

Unit Test:

 @Test@Transactionalpublic void createNewWorkWorkWhenCreatedJobItemAndQuantitiesPoolShouldBeCreated() throws Exception {    mockMvc.perform(post("/api/tracker/jobs/work")        .contentType(TestUtil.APPLICATION_JSON_UTF8)        .content(TestUtil.convertObjectToJsonBytes(workRequest)))        .andExpect(status().isCreated())        .andDo(mvcResult -> {            String json = mvcResult.getResponse().getContentAsString();            workRequestResponse = (WorkRequestResponse) TestUtil.convertJSONStringToObject(json, WorkRequestResponse.class);        });    Work work = workService.findWorkById(workRequestResponse.getWorkId());    assertThat(work.getJobItem().getJobItemName()).isEqualTo(workRequest.getJobItem().getJobItemName());    assertThat(work.getJobItem().getQuantities()).hasSize(workRequest.getQuantities().size());    assertThat(work.getJobItem().getQuantityPools()).hasSize(workRequest.getQuantities().size());}

One way to retrieve an arbitrary, generic value from the JSON response is to leverage the jsonPath() matcher from the MockMVC library and couple it with a custom matcher that captures all values it is asked to match.

First, the custom matcher:

import org.hamcrest.BaseMatcher;/** * Matcher which always returns true, and at the same time, captures the * actual values passed in for matching. These can later be retrieved with a * call to {@link #getLastMatched()} or {@link #getAllMatched()}. */public static class CapturingMatcher extends BaseMatcher<Object> {    private List<Object> matchedList = new ArrayList<>();    @Override    public boolean matches(Object matched) {        matchedList.add(matched);        return true;    }    @Override    public void describeTo(Description description) {        description.appendText("any object");    }    /**     * The last value matched.     */    public Object getLastMatched() {        return matchedList.get(matchedList.size() - 1);    }    /**     * All the values matched, in the order they were requested for     * matching.     */    public List<Object> getAllMatched() {        return Collections.unmodifiableList(matchedList);    }}

Now, use the custom matcher to capture values and use the jsonPath() matcher to identify what should be captured:

@Test@WithMockUser(username = "reviewer", authorities = {ROLE_USER})public void testGetRemediationAction() throws Exception {    CapturingMatcher capturingMatcher = new CapturingMatcher();    // First request a list of all the available actions    mvc.perform(get("/api/remediation/action").accept(VERSION_1_JSON))            .andExpect(status().isOk())            .andExpect(jsonPath("$.content[*].remediations[*].id", hasSize(12)))            .andExpect(jsonPath("$.content[*].remediations[*].id", capturingMatcher));    // Grab an ID from one of the available actions    Object idArray = capturingMatcher.getLastMatched();    assertThat(idArray).isInstanceOf(JSONArray.class);    JSONArray jsonIdArray = (JSONArray) idArray;    String randomId = (String) jsonIdArray.get(new Random().nextInt(12));    // Now retrieve the chosen action    mvc.perform(get("/api/remediation/action/" + randomId).accept(VERSION_1_JSON))            .andExpect(status().isOk())            .andExpect(jsonPath("$.id", is(randomId)));}