import static org.hamcrest.CoreMatchers.allOf;
import static org.hamcrest.CoreMatchers.anyOf;
import static org.hamcrest.CoreMatchers.both;
import static org.hamcrest.CoreMatchers.containsString;
import static org.hamcrest.CoreMatchers.equalTo;
import static org.hamcrest.CoreMatchers.everyItem;
import static org.hamcrest.CoreMatchers.hasItems;
import static org.hamcrest.CoreMatchers.not;
import static org.hamcrest.CoreMatchers.sameInstance;
import static org.hamcrest.CoreMatchers.startsWith;
import static org.junit.Assert.assertArrayEquals;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertNotSame;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertSame;
import static org.junit.Assert.assertThat;
import static org.junit.Assert.assertTrue;

import java.util.Arrays;

import org.hamcrest.core.CombinableMatcher;
import org.junit.Test;

public class AssertTests {
 @Test
 public void testAssertArrayEquals() {
  byte[] expected = "trial".getBytes();
  byte[] actual = "trial".getBytes();
  assertArrayEquals("failure - byte arrays not same", expected, actual);
 }

 @Test
 public void testAssertEquals() {
  assertEquals("failure - strings are not equal", "text", "text");
 }

 @Test
 public void testAssertFalse() {
  assertFalse("failure - should be false", false);
 }

 @Test
 public void testAssertNotNull() {
  assertNotNull("should not be null", new Object());
 }

 @Test
 public void testAssertNotSame() {
  assertNotSame("should not be same Object", new Object(), new Object());
 }

 @Test
 public void testAssertNull() {
  assertNull("should be null", null);
 }

 @Test
 public void testAssertSame() {
  Integer aNumber = Integer.valueOf(768);
  assertSame("should be same", aNumber, aNumber);
 }

 // JUnit Matchers assertThat
 @Test
 public void testAssertThatBothContainsString() {
  assertThat("albumen", both(containsString("a")).and(containsString("b")));
 }

 @Test
 public void testAssertThatHasItems() {
  assertThat(Arrays.asList("one", "two", "three"), hasItems("one", "three"));
 }

 @Test
 public void testAssertThatEveryItemContainsString() {
  assertThat(Arrays.asList(new String[] { "fun", "ban", "net" }), everyItem(containsString("n")));
 }

 // Core Hamcrest Matchers with assertThat
 @Test
 public void testAssertThatHamcrestCoreMatchers() {
  assertThat("good", allOf(equalTo("good"), startsWith("good")));
  assertThat("good", not(allOf(equalTo("bad"), equalTo("good"))));
  assertThat("good", anyOf(equalTo("bad"), equalTo("good")));
  assertThat(7, not(CombinableMatcher.<Integer> either(equalTo(3)).or(equalTo(4))));
  assertThat(new Object(), not(sameInstance(new Object())));
 }

 @Test
 public void testAssertTrue() {
  assertTrue("failure - should be true", true);
 }
}

<dependency>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-test</artifactId>
 <scope>test</scope>
</dependency>
<dependency>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
 <groupId>org.projectlombok</groupId>
 <artifactId>lombok</artifactId>
 <version>1.16.20</version>
 <scope>provided</scope>
</dependency>

package com.mgiglione.model;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

@Getter @Setter @NoArgsConstructor @AllArgsConstructor @Builder
public class Manga {
  private String title;
  private String description;
  private Integer volumes;
  private Double score;
}

package com.mgiglione.model;
import java.util.List;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
@Getter @Setter @NoArgsConstructor
public class MangaResult {
  private List<Manga> result;
}

package com.mgiglione.service;

import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

import com.mgiglione.model.Manga;
import com.mgiglione.model.MangaResult;

@Service
public class MangaService {

  Logger logger = LoggerFactory.getLogger(MangaService.class);
  private static final String MANGA_SEARCH_URL="http://api.jikan.moe/search/manga/";
  
  @Autowired
  RestTemplate restTemplate;
  
  public List<Manga> getMangasByTitle(String title) {
    return restTemplate.getForEntity(MANGA_SEARCH_URL+title, MangaResult.class).getBody().getResult();
  }
}

package com.mgiglione.controller;

import java.util.List;
import java.util.concurrent.CompletableFuture;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.scheduling.annotation.Async;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

import com.mgiglione.model.Manga;
import com.mgiglione.service.MangaService;

@RestController
@RequestMapping(value = "/manga")
public class MangaController {

  Logger logger = LoggerFactory.getLogger(MangaController.class);
  
  @Autowired
  private MangaService mangaService;  
  
  @RequestMapping(value = "/async/{title}", method = RequestMethod.GET)
  @Async
  public CompletableFuture<List<Manga>> searchASync(@PathVariable(name = "title") String title) {
    return CompletableFuture.completedFuture(mangaService.getMangasByTitle(title));
  }
  
  @RequestMapping(value = "/sync/{title}", method = RequestMethod.GET)
  public @ResponseBody <List<Manga>> searchSync(@PathVariable(name = "title") String title) {
    return mangaService.getMangasByTitle(title);
  }
}

mvn spring-boot:run

curl http://localhost:8080/manga/async/ken
curl http://localhost:8080/manga/sync/ken

{ 
  "title":"Rurouni Kenshin: Meiji Kenkaku Romantan",
  "description":"Ten years have passed since the end of Bakumatsu, an era of war that saw the uprising of citizens against the Tokugawa shogunate. The revolutionaries wanted to create a time of peace, and a thriving c...",
  "volumes":28,
  "score":8.69
},
{ 
  "title":"Sun-Ken Rock",
  "description":"The story revolves around Ken, a man from an upper-class family that was orphaned young due to his family's involvement with the Yakuza; he became a high school delinquent known for fighting. The only...",
  "volumes":25,
  "score":8.12
},
{ 
  "title":"Yumekui Kenbun",
  "description":"For those who suffer nightmares, help awaits at the Ginseikan Tea House, where patrons can order much more than just Darjeeling. Hiruko is a special kind of a private investigator. He's a dream eater....",
  "volumes":9,
  "score":7.97
}

package com.mgiglione.service.test.unit;
import static org.mockito.ArgumentMatchers.any;
import static org.mockito.Mockito.when;
import java.io.IOException;
import java.util.List;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.mock.mockito.MockBean;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.web.client.RestTemplate;
import static org.assertj.core.api.Assertions.assertThat;

import com.mgiglione.model.Manga;
import com.mgiglione.model.MangaResult;
import com.mgiglione.service.MangaService;
import com.mgiglione.utils.JsonUtils;

@RunWith(SpringRunner.class)
@SpringBootTest
public class MangaServiceUnitTest {
  
  @Autowired
  private MangaService mangaService;
  
  // MockBean is the annotation provided by Spring that wraps mockito one
  // Annotation that can be used to add mocks to a Spring ApplicationContext.
  // If any existing single bean of the same type defined in the context will be replaced by the mock, if no existing bean is defined a new one will be added.
  @MockBean
  private RestTemplate template;
  
  @Test
  public void testGetMangasByTitle() throws IOException {
    // Parsing mock file
    MangaResult mRs = JsonUtils.jsonFile2Object("ken.json", MangaResult.class);
    // Mocking remote service
    when(template.getForEntity(any(String.class), any(Class.class))).thenReturn(new ResponseEntity(mRs, HttpStatus.OK));
    // I search for goku but system will use mocked response containing only ken, so I can check that mock is used.
    List<Manga> mangasByTitle = mangaService.getMangasByTitle("goku");
    assertThat(mangasByTitle).isNotNull()
      .isNotEmpty()
      .allMatch(p -> p.getTitle()
        .toLowerCase()
        .contains("ken"));
  }
  
}

package com.mgiglione.service.test.unit;

import static org.hamcrest.Matchers.is;
import static org.mockito.ArgumentMatchers.any;
import static org.mockito.Mockito.when;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.asyncDispatch;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.request;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
import static org.springframework.test.web.servlet.setup.MockMvcBuilders.standaloneSetup;

import java.util.ArrayList;
import java.util.List;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.mock.mockito.MockBean;
import org.springframework.http.MediaType;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.MvcResult;
import org.springframework.web.context.WebApplicationContext;

import com.mgiglione.controller.MangaController;
import com.mgiglione.model.Manga;
import com.mgiglione.service.MangaService;

@SpringBootTest
@RunWith(SpringRunner.class)
public class MangaControllerUnitTest {

  MockMvc mockMvc;
  
  @Autowired
  protected WebApplicationContext wac;
  
  @Autowired
  MangaController mangaController;
  
  @MockBean
  MangaService mangaService;
  
  /**
   * List of samples mangas
   */
  private List<Manga> mangas;
  
  @Before
  public void setup() throws Exception {
    this.mockMvc = standaloneSetup(this.mangaController).build();// Standalone context
    // mockMvc = MockMvcBuilders.webAppContextSetup(wac)
    // .build();
    Manga manga1 = Manga.builder()
      .title("Hokuto no ken")
      .description("The year is 199X. The Earth has been devastated by nuclear war...")
      .build();
    Manga manga2 = Manga.builder()
      .title("Yumekui Kenbun")
      .description("For those who suffer nightmares, help awaits at the Ginseikan Tea House, where patrons can order much more than just Darjeeling. Hiruko is a special kind of a private investigator. He's a dream eater....")
      .build();
    mangas = new ArrayList<>();
    mangas.add(manga1);
    mangas.add(manga2);
  }
  
  @Test
  public void testSearchSync() throws Exception {
    // Mocking service
    when(mangaService.getMangasByTitle(any(String.class))).thenReturn(mangas);
    mockMvc.perform(get("/manga/sync/ken").contentType(MediaType.APPLICATION_JSON))
      .andExpect(status().isOk())
      .andExpect(jsonPath("$[0].title", is("Hokuto no ken")))
      .andExpect(jsonPath("$[1].title", is("Yumekui Kenbun")));
  }

  @Test
  public void testSearchASync() throws Exception {
    // Mocking service
    when(mangaService.getMangasByTitle(any(String.class))).thenReturn(mangas);
    MvcResult result = mockMvc.perform(get("/manga/async/ken").contentType(MediaType.APPLICATION_JSON))
      .andDo(print())
      .andExpect(request().asyncStarted())
      .andDo(print())
      // .andExpect(status().is2xxSuccessful()).andReturn();
      .andReturn();
    // result.getRequest().getAsyncContext().setTimeout(10000);
    mockMvc.perform(asyncDispatch(result))
      .andDo(print())
      .andExpect(status().isOk())
      .andExpect(jsonPath("$[0].title", is("Hokuto no ken")));
  }
}

package com.mgiglione.service.test.integration;

import static org.assertj.core.api.Assertions.assertThat;

import java.util.List;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

import com.mgiglione.model.Manga;
import com.mgiglione.service.MangaService;

@RunWith(SpringRunner.class)
@SpringBootTest
public class MangaServiceIntegrationTest {

  @Autowired
  private MangaService mangaService;
  
  @Test
  public void testGetMangasByTitle() {
      List<Manga> mangasByTitle = mangaService.getMangasByTitle("ken");
      assertThat(mangasByTitle).isNotNull().isNotEmpty();
  }
}

package com.mgiglione.service.test.integration;
import static org.hamcrest.Matchers.hasItem;
import static org.hamcrest.Matchers.is;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.asyncDispatch;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.request;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
import static org.springframework.test.web.servlet.setup.MockMvcBuilders.standaloneSetup;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.http.MediaType;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.MvcResult;
import org.springframework.web.context.WebApplicationContext;

import com.mgiglione.controller.MangaController;

@SpringBootTest
@RunWith(SpringRunner.class)
public class MangaControllerIntegrationTest {

  // @Autowired
  MockMvc mockMvc;
  
  @Autowired
  protected WebApplicationContext wac;
  
  @Autowired
  MangaController mangaController;
  
  @Before
  public void setup() throws Exception {
    this.mockMvc = standaloneSetup(this.mangaController).build();// Standalone context
    // mockMvc = MockMvcBuilders.webAppContextSetup(wac)
    // .build();
  }
  
  @Test
  public void testSearchSync() throws Exception {
    mockMvc.perform(get("/manga/sync/ken").contentType(MediaType.APPLICATION_JSON))
      .andExpect(status().isOk())
      .andExpect(jsonPath("$.*.title", hasItem(is("Hokuto no Ken"))));
  }
  
  @Test
  public void testSearchASync() throws Exception {
    MvcResult result = mockMvc.perform(get("/manga/async/ken").contentType(MediaType.APPLICATION_JSON))
      .andDo(print())
      .andExpect(request().asyncStarted())
      .andDo(print())
      .andReturn();
    mockMvc.perform(asyncDispatch(result))
      .andDo(print())
      .andExpect(status().isOk())
      .andExpect(jsonPath("$.*.title", hasItem(is("Hokuto no Ken"))));
  }
}