Mock為測試代碼帶來混亂和重復
下面的代碼使用 EasyMock 測試：EmployeeBO用EmployeeDAO存儲新員工信息和更新當前員工信息。
@Before public void setUp() {
mockEmployeeDAO = createMock(EmployeeDAO.class);
employeeBO = new EmployeeBO(mockEmployeeDAO);
employee = new Employee("Alex", "CA", "US");
}
@Test public void shouldAddNewEmployee() {
mockEmployeeDAO.insert(employee);
replay(mockEmployeeDAO);
employeeBO.addNewEmployee(employee);
verify(mockEmployeeDAO);
}
@Test public void shouldUpdateEmployee() {
mockEmployeeDAO.update(employee);
replay(mockEmployeeDAO);
employeeBO.updateEmployee(employee);
verify(mockEmployeeDAO);
}測試方法shouldAddNewEmployee用于驗證測試對象（employeeBO ）和Mock（mockEmployeeDAO ）之間交互是否正確。它期望employeeBO調用mockEmployeeDAO中的insert方法，并將接收到的Employee實例傳遞給該方法。shouldAddNewEmployee方法雖然簡單，但其中含有一些沒有實際目的的代碼，這為我們的測試帶來了混亂：
- 重復調用replay，通知EasyMock所有期望的工作已完成。
- 重復調用verify，通知EasyMock所有期望的工作已驗證完成。
Mock的使用常常遵循下面的模式：
- 建立Mock和期望
- 執行要測試的代碼
- 驗證執行結果是否符合期望
這種模式會在測試代碼中引入重復，這在測試方法shouldAddNewEmployee()和shouldUpdateEmployee()中很明顯。使用 EasyMockTemplate 可以減少代碼混亂和重復：
/**
* Understands a template for usage of EasyMock mocks.
* @author Alex Ruiz
*/
public abstract class EasyMockTemplate {
/** Mock objects managed by this template */
private final List<Object> mocks = new ArrayList<Object>();
/**
* Constructor.
* @param mocks the mock objects this template will manage.
* @throws IllegalArgumentException if the list of mock objects is null or empty.
* @throws IllegalArgumentException if the list of mock objects contains a null value.
*/
public EasyMockTemplate(Object... mocks) {
if (mocks == null) throw new IllegalArgumentException("The list of mock objects should not be null");
if (mocks.length == 0) throw new IllegalArgumentException("The list of mock objects should not be empty");
for (Object mock : mocks) {
if (mock == null) throw new IllegalArgumentException("The list of mocks should not include null values");
this.mocks.add(mock);
}
}
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