java - 如何使用通配符模拟通用方法的行为

我正在使用EasyMock(3.2)。我想为基于Spring Security的部分安全系统编写测试。我想模拟 Authentication ，以便它返回授权的空列表。其方法声明如下:

 Collection<? extends GrantedAuthority> getAuthorities();

所以我写了一个测试:

Authentication authentication = createMock(Authentication.class);
Collection<? extends GrantedAuthority> authorities = Collections.emptyList();
expect(authentication.getAuthorities()).andReturn(authorities);

但是编译器抱怨andReturn调用的第三行:
The method andReturn(Collection<capture#1-of ? extends GrantedAuthority>) in the type IExpectationSetters<Collection<capture#1-of ? extends GrantedAuthority>> is not applicable for the arguments (Collection<capture#2-of ? extends GrantedAuthority>
我究竟做错了什么？

更新:

当我将authorities的声明更改为:

Collection<GrantedAuthority> authorities = Collections.emptyList();

如建议的那样，它仍然无法编译，但是错误有些不同:
The method andReturn(Collection<capture#1-of ? extends GrantedAuthority>) in the type IExpectationSetters<Collection<capture#1-of ? extends GrantedAuthority>> is not applicable for the arguments (Collection<GrantedAuthority>)
我确保两个声明GrantedAuthority中的org.springframework.security.core.GrantedAuthority实际上是相同的。

最佳答案

从集合声明中删除项目类型，您会收到警告，但测试仍然有效。

@Test
public void testFoo()
    {
    // setup
    Authentication mockAuthentication = createMock(Authentication.class);
    Collection authorities = Collections.emptyList();
    expect(mockAuthentication.getAuthorities()).andReturn(authorities);

    // exercise
    EasyMock.replay(mockAuthentication);
    Collection<? extends GrantedAuthority> retAuth = mockAuthentication.getAuthorities();

    // verify
    EasyMock.verify(mockAuthentication);
    assertEquals(authorities, retAuth);
    }