用EasyMock辅助JUnit测试

由于JUnit很难操控外部环境的资源,如数据库、网络、Servlet引擎；通过MOCK对象就能模拟外部环境的资源，从而保证JUnit的正常运行。

其中EasyMock是一套简单的生成MOCK对象类库，用它可以非常容易的辅助JUnit完成单元测试；如下：

public class UseMock {

 @Test
 public void testMock() {
  HttpServletRequest request = EasyMock.createMock(HttpServletRequest.class);
  request.getParameter("ffff");
  EasyMock.expect(request.getParameter("ffff")).andReturn("33333");
  EasyMock.expect(request.getRealPath("/")).andReturn("fffffffff").anyTimes();
  //EasyMock.expectLastCall().andReturn("ffff").times(1);
  EasyMock.replay(request);
  System.out.println(request.getRealPath("/"));
  System.out.println(request.getRealPath("/"));
  EasyMock.verify(request);
 }
}

void testMock() {
	HttpServletRequest request = mock(HttpServletRequest) {
		getParameter("ffff").returns("33333")
		getRealPath("/").returns("fffffffff").stub()
	}
	play {
		println request.getParameter("ffff")
		println request.getRealPath("/")
		println request.getRealPath("/")
	}
}

 //you can use flexible argument matchers, e.g:
 when(mock.someMethod(anyString())).thenReturn(10);

 //setting exception to be thrown:
 when(mock.someMethod("some arg")).thenThrow(new RuntimeException());

 //you can set different behavior for consecutive method calls.
 //Last stubbing (e.g: thenReturn("foo")) determines the behavior of further consecutive calls.
 when(mock.someMethod("some arg"))
  .thenThrow(new RuntimeException())
  .thenReturn("foo");