org.mockito.exceptions.misusing.MissingMethodInvocationException

Question

I am getting following exceptions when I run Junit test.

org.mockito.exceptions.misusing.MissingMethodInvocationException:

when() requires an argument which has to be 'a method call on a mock'. For example:

   when(mock.getArticles()).thenReturn(articles);

Also, this error might show up because:

1. you stub either of: final/private/equals()/hashCode() methods. Those methods cannot be stubbed/verified.
2. inside when() you don't call method on mock but on some other object.
3. the parent of the mocked class is not public. It is a limitation of the mock engine.

Following is my code and the exception was thrown at the second when statement. I don't think that my test code didn't violate what the exception claims. I spent for a while, but couldn't figure out. Could someone help? What I need to test is getPermProducts method. In the getPermProducts method, I want to ignore isTempProduct method. So, when p1 came, I want it returns false, and when p2 came, I want it returns true etc..

@Named(ProductManager.NAME)
public class ProductManager {

    @Resource(name = ProductService.NAME)
    private ProductService productService;

    public List<Product> getPermProducts(Set<Product> products) {
        Iterator<Product> it = products.iterator();
        List<Product> cProducts = new ArrayList<Product>();
        Product p;
        while (it.hasNext()) {
            p = it.next();
            if (!isTempProduct(p)) {
            cProducts.add(p);
            }
        }
        return cProducts;
    }

    public Boolean isTempProduct(Product product) {
    if (product instanceof PermProduct) {
    return false;
    }
    Set<ProductItems> pItems = product.getProductItems();
        if (pItems.isEmpty()) {
        return false;
    }
    Iterator<ProductItem> itr = pItems.iterator();
    while (itr.hasNext()) {
        if (itr.next() instanceof TempItem) {
            return true;
        }
    }
    return false;
}

public Product getProduct(Integer productId) {
    Product p = productService.getProduct(productId);
    return p;
    }

}



@RunWith(MockitoJUnitRunner.class)
public class ProductManagerTest {


    @InjectMocks
    private ProductManager mockProductManager;
    @Mock
    private ProductService mockProductService;//not being used here

    private static final Integer PRODUCT_ID_1 = 1;
    private static final Integer PRODUCT_ID_2 = 2;

    @Test
    public void getProduct(){
        Product p1 = mock(PermProduct.class);
            p1.setProductId(PRODUCT_ID_1);
        when(mockProductManager.getProductId()).thenReturn(PRODUCT_ID_1);
        when(mockProductManager.isTempProduct(p1)).thenReturn(false);
            Product p2 = mock(TempProduct.class);
            p2.setProductId(PRODUCT_ID_2);
            when(mockProductManager.isTempProduct(p2)).thenReturn(true);
            List<Product> products = Mock(List.class);
            products.add(p1);
            products.add(p2);
            Iterator<Product> pIterator = mock(Iterator.class);
            when(prodcuts.iterator()).thenReturn(pIterator);
            when(pIterator.hasNext()).thenReturn(true, true, false);
    when(pIterator.next()).thenReturn(p1, p2);
            asserEquals(1, mockProductManager.getPermProducts(products).size());

    }

}

SOLUTION: I updated my test based on enterbios's answer. I used partial mocking, but as enterbios suggested, we should avoid it, but sometimes we need it. I found that we can have both non-mocked and partial mocked class same time.

@RunWith(MockitoJUnitRunner.class)
public class ProductManagerTest {

    @InjectMocks
    private ProductManager productManager;//not being used here
    @Mock
    private ProductService mockProductService;//not being used here

    @Spy
    private OtherService other = new OtherService();//not being used here

    @InjectMocks
    final ProductManager partiallyMockedProductManager = spy(new ProductManager());

    private static final Integer PRODUCT_ID_1 = 1;
    private static final Integer PRODUCT_ID_2 = 2;

    @Test
    public void getProduct() {
        Product p1 = new PermProduct();
        p1.setProductId(PRODUCT_ID_1);
        Product p2 = new Product();
        p2.setProductId(PRODUCT_ID_2);
        List<Product> products = new ArrayList<Product>();
        products.add(p1);
        products.add(p2);

        doReturn(false).when(partiallyMockedProductManager).isTempProduct(p1);
        doReturn(true).when(partiallyMockedProductManager).isTempProduct(p2);
        assertEquals(1, partiallyMockedProductManager.getPermProducts(products).size());
        verify(partiallyMockedProductManager).isTempProduct(p1);
        verify(partiallyMockedProductManager).isTempProduct(p2);
    }
}

Answer 1

Your mockProductManager is actually not a mock but an instance of ProductManager class. You shouldn't mock a tested object. The way to mock some methods from tested object is using a spy but I recommend you to not use them, or even to not think about them unless you're fighting with some ugly legacy code. I think your second 'when' should be replaced with assertion, like:

assertFalse(mockProductManager.isTempProduct(p1));

because what you really want to check in this test is if productManager.isTempProduct(p1) returns false for all instances of PermProduct. To verify results of some method calls/objects states you should use assertions. To make your life with assertions easier you can take a look on some helpful libraries like Hamcrest or FEST (http://docs.codehaus.org/display/FEST/Fluent+Assertions+Module). FEST is simpler for beginners I think.