For example, you have a page (shown below) to load and display all the products. It uses the ProductService to do that.
<html>
<body>
<table>
<tr wicket:id="eachProduct">
<td wicket:id="name">pen</td>
</tr>
</table>
</body>
</html>
public class ProductListingPage extends WebPage {
@SpringBean
private ProductService productService;
public ProductListingPage() {
List<Product> products = productService.getAll();
ListView<Product> eachProduct = new ListView<Product>("eachProduct",
products) {
private static final long serialVersionUID = 1L;
@Override
protected void populateItem(ListItem<Product> item) {
item.add(new Label("name", item.getModelObject().getName()));
}
};
add(eachProduct);
}
}
public interface ProductService {
List<Product> getAll();
void add(Product p);
void delete(Product p);
}As usual, to test it, you will create a mock object for the ProductSerivce (see below). However, the ProductSerivce interface contains some unneeded methods such as add() and delete(). Those methods are of no use to this test. Normally, you have to implement such methods in your mock object nonetheless:
@Test
public class ProductListingPageTest {
public class MockService implements ProductService {
public List<Product> getAll() {
List<Product> products = new ArrayList<Product>();
products.add(new Product("ball pen"));
products.add(new Product("eraser"));
return products;
}
public void add(Product p) {
}
void delete(Product p) {
}
}
public void testListing() {
ProductService mock = new MockService();
MockableSpringBeanInjector.mockBean("productService", mock);
DefaultSelenium selenium = WebPageTestContext.getSelenium();
WicketSelenium ws = new WicketSelenium(selenium);
ws.openBookmarkablePage(ProductListingPage.class);
assert selenium.getText("wicket=//eachProduct[0]//name").equals(
"ball pen");
assert selenium.getText("wicket=//eachProduct[1]//name").equals(
"eraser");
}
}The problem is that, on one hand, such dummy methods are just noise in the code; on the other hand, if new methods are added to the ProductService interface or the method signatures change, the code will break.
To solve this problem, you can use the ChangeResistantMockFactory class provided by Wicket Page Test as shown below:
@Test
public class ProductListingPageTest {
private ChangeResistantMockFactory mockFactory = new ChangeResistantMockFactory(this);
public abstract class MockService implements ProductService {
public List<Product> getAll() {
List<Product> products = new ArrayList<Product>();
products.add(new Product("ball pen"));
products.add(new Product("eraser"));
return products;
}
}
public void testListing() {
ProductService mock = mockFactory
.implementAbstractMethods(MockService.class);
MockableSpringBeanInjector.mockBean("productService", mock);
...
}
}Note that your MockService class is now declared as abstract as it only implements the getAll() while leaving the add() and delete() methods abstract. In the test code, you use the ChangeResistantMockFactory to generate a sub-class of MockService implementing all the abstract methods in it and then create an instance of it.