test driven

service test with PowerMockito

setup PowerMockito

@RunWith(PowerMockRunner.class)
@PrepareForTest({ProductServiceImpl.class, ProductGenerator.class, Product.class})
public class ProductServiceImplTest {
    
    @Mock
    private ProductRepo productRepo;
    
    @Mock
    private EventBus eventBus;
    
    @Rule
    private ExpectedException exception = ExpectedException.none();
    
    private ProductServiceImpl productService;
    
    @Before
    public void init(){
        productService = spy(new ProductServiceImpl(productRepo, eventBus));
        //Whitebox.setInternalState(productService, "productRepo", productRepo); //当为private时
    }   
}

• @PrepareForTest: 包含静态方法的类、待测试的类等
• 待测试类要spy，而不是用mock。 另外，@InjectMocks不支持mock自身方法。当内部字段为private时，采用WhiteBox来设置内部状态
• 异常验证可以用@Test(expected=Xxx.class), 但要深入时，用@Rule ExpectedException。

mock or suppress

• mock's public:

when(productRepo.save(product)).thenReturn(product);

• spy's public:

doReturn(new Product()).when(productService).findByName("p1");

• spy's private:

doReturn(new Product()).when(productService, "findByNo", "n1");

• spy's private void:

doNothing().when(productService, "checkCategoryId", 0L);

• spy's private void:

doThrow(new RuntimeException("category.invalid")).when(productService, "checkCategoryId", 0L);

• suppress static constructor:

@SuppressStaticInitializationFor("top.zhacker.testdriven.product.model.Product")

• suppress instance constructor:

suppress(constructor(Product.class));

• suppress method invoke:

suppress(method(Product.class,"check", Product.class));

• mock static method:

mockStatic(ProductGenerator.class); when(ProductGenerator.getNextId()).thenReturn("no");

• mock static method void:

mockStatic(Product.class); doNothing().when(Product.class, "check", any());

• mock static method void:

mockStatic(Product.class); doThrow(new RuntimeException("check.fail")).when(Product.class, "check", any());

• mock constructor:

whenNew(Product.class).withArguments("invalid").thenReturn(mock(Product.class));

• mock different returns

    when(productRepo.findByName(any())).then(invocationOnMock->{
        String name = invocationOnMock.getArgument(0);
        if(name.startsWith("pa")) return new Product("pa");
        if(name.startsWith("pb")) return new Product("pb");
        return null;
    });

verify

• exception:

exception.expect(RuntimeException.class);
exception.expectMessage("check.fail");

• params:

    verify(productRepo).save((Product)argThat(p->{ //overload
        Product toSave = (Product)p; //overload
        assertEquals("pa", toSave.getName());
        assertNotNull(toSave.getCreatedAt());
        assertNotNull(toSave.getNo());
        assertNotNull(toSave.getUrl());
        return true;
    }));
   

• verify private:

verifyPrivate(productService).invoke("updateProduct", product);

• verify static:

verifyStatic(times(1)); Product.check(product); // invoke static verify, important