在 Spring Boot 应用程序中使用 Mockito

Question

我对SpringBoot很熟悉，写过一个小应用。它有一个ProductRepository 扩展CrudRepository。我的ProductService 是这样的：

public interface ProductService {
  Iterable<Product> listAllProducts();
  Product getProductById(Integer id);
  Product saveProduct(Product product);
  void deleteProduct(Integer id);
}

ProductServiceImpl 类自动连接到 ProductRepository 并提供使用 ProductRepository 的实现。

我的应用程序按预期运行，这就是我测试存储库的方式。

@RunWith(SpringRunner.class)
@SpringBootTest(classes = {RepositoryConfiguration.class})
public class ProductRepositoryTest {
  private ProductRepository productRepository;
  @Autowired
  public void setProductRepository(ProductRepository productRepository) {
    this.productRepository = productRepository;
  }
  @Test
  public void testSaveProduct(){
    //setup product
    Product product = new Product();
    product.setDescription("Shirt");
    product.setPrice(new BigDecimal("18.95"));
    product.setProductId("1234");        
    assertNull(product.getId()); //null before save
    productRepository.save(product);
    assertNotNull(product.getId()); //not null after save
    //fetch from DB
    Product fetchedProduct = productRepository.findOne(product.getId());
    //should not be null
    assertNotNull(fetchedProduct);      
 }
}

我想知道如何在没有外部依赖的情况下对ProductRepository 进行单元测试（上面的测试具有，因此不符合单元测试的条件。我相信它更像是一个集成测试）。

另外，我如何对我的ProductService 进行单元测试？我尝试用 Mockito 模拟 ProductRepository 和 Product，如下所示：

public class ProductServiceImplTest {
  private ProductServiceImpl productServiceImpl;
  private ProductRepository productRepository;
  private Product product;

  @Before
  public void setupMock() {
    MockitoAnnotations.initMocks(this);
    productServiceImpl=new ProductServiceImpl();
    productRepository = mock(ProductRepository.class);
    product = mock(Product.class);
  }

  @Test
  public void testRetrieveById() throws Exception {
   when(productRepository.findOne(5)).thenReturn(product);
    assertEquals(product, productServiceImpl.getProductById(5));
  }
}

但这就是我得到的：

java.lang.NullPointerException
at    
  ProductServiceImpl.getProductById(ProductServiceImpl.java:24)
at  ProductServiceImplTest.testRetrieveById(ProductServiceImplTest.java:36)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at  sun.reflect.NativeMethodAccessorImpl.invoke
(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke
(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at  org.junit.runners.model.FrameworkMethod$1.runReflectiveCall
   (FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run
(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:51)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:237)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)

我是否正确使用了Mockito.mock()？另外，如果我改用Mockito.spy()，会有什么区别？任何帮助将不胜感激。

Answer 1

如果您想编写单元测试，请删除所有用于集成测试的不必要注释。

您还需要在@Before 方法中启动模拟：

public class ProductServiceImplTest {
  @InjectMocks
  private ProductServiceImpl productServiceImpl;
  @Mock
  private ProductRepository productRepository;
  @Mock
  private Product product;

  @Before
  public void setupMock() {
    MockitoAnnotations.initMocks(this);
  }

我认为在您的情况下，使用 mock 应该就足够了。

您应该使用 spy 的唯一时间是在您正在测试的类上调用它，在您的情况下是：

productServiceImpl=new ProductServiceImpl();
prodServiceSpy = spy(productServiceImpl);

并模拟一些您不想调用的实现方法，或使用测试场景所需的自定义实现来调用。