Writing unit test for Filter (OncePerRequestFilter) in Spring boot

Question

I have Filter class that extends OncePerRequestFilter. This filter is used for capturing audit data and then pass on to an async method for persisting in db. I need to write test cases for this entire scenario. How to achieve this? I don't have any great expertise on Junit.

public class AuditFilter extends OncePerRequestFilter {

  private static final Logger LOGGER = LoggerFactory.getLogger(AuditFilter.class);
  private AuditLogManager auditLogManager;
  private String auditMode;
  private List<String> urlPatterns;

  /**
   * @param auditLogManager - processes the audit logs.
   * @param auditMode - modes of auditing (OFF,BASIC,DETAILED).
   * @param urlPatterns - the URL patterns for which auditing to be done.
   */
  public AuditFilter(final AuditLogManager auditLogManager, final String auditMode,
      final List<String> urlPatterns) {
    this.auditLogManager = auditLogManager;
    this.auditMode = auditMode;
    this.urlPatterns = urlPatterns;
  }

  @Override()
  protected void doFilterInternal(final HttpServletRequest request,
      final HttpServletResponse response, final FilterChain filterChain)
      throws ServletException, IOException {
    //capture audit data from request
      try {
        filterChain.doFilter(wrappedRequest, wrappedResponse);
      } finally {
        //capture audit data from response
        // Executing asynchronous call. auditLogManager uses @Async annotation. Need i=integration test for auditLogManager code also
        auditLogManager.log(auditInfo, auditMode);
      }    
  } 
}

I need to unit test every action performed by AuditFilter and AuditLogManager(class having asynchronous method) during maven build.

Answer 1

This might be a late response. But an alternate approach that can be used.

With current spring 2.5.5, one option is to use RestTemplate approach

// use below annotation at class level
// the WebEnvironment with Random_port, this is required for test case
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)

@Test
    void postTest() {
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_JSON);
        String bodyContent = "{\"appAPI\":\"<SOME-API-CODE-or-USER-NAME>\"}";

        HttpEntity<String> requestEntity = new HttpEntity<>(bodyContent, headers);
        //END POINT exposed in myapp, which will be used to provide the token.
        String token = restTemplate
                .postForObject("/myapp/authenticate",requestEntity, String.class);

        ObjectMapper mapper = new ObjectMapper();
        JsonNode root;
        try {
            root = mapper.readTree(token);
            JsonNode tokenVal = root.path("jwtToken");
            System.out.println("TKN: "+tokenVal.asText());
            Assert.isTrue(tokenVal.asText()!=null, "Token received successfully");
        } catch (JsonProcessingException e) {
            Assert.isTrue(false,"Exception occurred: "+e.getMessage());
        }

    }

• In my case, i had a Java POJO for jwt response, so the response from the POST endpoint was a POJO so using ObjectMapper to parse and validate.