@Test
  public void getHeaders() throws Exception {
    handler = new RequestHandler() {

      @Override
      public void handle(Request request, HttpServletResponse response) {
        response.setStatus(HTTP_OK);
        response.addHeader("a", "1");
        response.addHeader("a", "2");
      }
    };
    HttpRequest request = get(url);
    assertTrue(request.ok());
    String[] values = request.headers("a");
    assertNotNull(values);
    assertEquals(2, values.length);
    assertTrue(Arrays.asList(values).contains("1"));
    assertTrue(Arrays.asList(values).contains("2"));
  }
Get header with multiple response values

@throws Exception
lib/src/test/java/com/github/kevinsawicki/http/HttpRequestTest.java