如何使用 Mockito 模拟 Java 中的泛型方法？
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How to mock generic method in Java with Mockito?
提问by Jon Erickson
How can we mock the IRouteHandlerRegistry? The error is Cannot resolve method thenReturn(IHandleRoute<TestRoute>)
我们怎么能嘲笑IRouteHandlerRegistry？错误是Cannot resolve method thenReturn(IHandleRoute<TestRoute>)
public interface RouteDefinition { }
public class TestRoute implements RouteDefinition { }
public interface IHandleRoute<TRoute extends RouteDefinition> {
Route getHandlerFor(TRoute route);
}
public interface IRouteHandlerRegistry {
<TRoute extends RouteDefinition> IHandleRoute<TRoute> getHandlerFor(TRoute route);
}
@Test
@SuppressWarnings("unchecked")
public void test() {
// in my test
RouteDefinition route = new TestRoute(); // TestRoute implements RouteDefinition
IRouteHandlerRegistry registry = mock(IRouteHandlerRegistry.class);
IHandleRoute<TestRoute> handler = mock(IHandleRoute.class);
// Error: Cannot resolve method 'thenReturn(IHandleRoute<TestRoute>)'
when(registry.getHandlerFor(route)).thenReturn(handler);
}
采纳答案by M Anouti
Even though TestRouteis a subtype of RouteDefinition, a IHandleRoute<TestRoute>is nota subtype of IHandleRoute<RouteDefinition>.
即使TestRoute是一个亚型RouteDefinition，一个IHandleRoute<TestRoute>是没有的一个亚型IHandleRoute<RouteDefinition>。
The whenmethod from Mockito returns an object of type OngoingStubbing<IHandleRoute<RouteDefinition>>. This is due to the compiler inferring the type parameter TRoutefrom the method
whenMockito 中的方法返回一个类型为 的对象OngoingStubbing<IHandleRoute<RouteDefinition>>。这是由于编译器TRoute从方法中推断出类型参数
<TRoute extends RouteDefinition> IHandleRoute<TRoute> getHandlerFor(TRoute route);
to be RouteDefinitionsince the argument passed to getHandlerForis declared of type RouteDefinition.
是RouteDefinition因为传递给的参数getHandlerFor被声明为类型RouteDefinition。
On the other hand, the thenReturnmethod is given an argument of type IHandleRoute<TestRoute>whereas it expects an IHandleRoute<RouteDefinition>, that is the type argument of the OngoingStubbingmentioned earlier. Hence the compiler error.
另一方面，该thenReturn方法被赋予一个类型参数，IHandleRoute<TestRoute>而它期望一个IHandleRoute<RouteDefinition>，即OngoingStubbing前面提到的类型参数。因此编译器错误。
To solve this, the simplest way is probably to change the declaration type of routeto be TestRoute:
要解决这个问题，最简单的方法可能是将声明类型更改route为TestRoute：
TestRoute route = new TestRoute();
IRouteHandlerRegistry registry = mock(IRouteHandlerRegistry.class);
IHandleRoute<TestRoute> handler = mock(IHandleRoute.class);
when(registry.getHandlerFor(route)).thenReturn(handler);
回答by Fariba
If you write like this it will be ok:
如果你这样写就可以了：
Mockito.doReturn(handler).when(registry).getHandlerFor(Mockito.any(route.class))
回答by Gualtiero Testa
Mockito.whenargument should be a method not a mock.
Mockito.when参数应该是一种方法而不是模拟。
The correct statement is:
when(registry.getHandlerFor (route)).thenReturn(handler)
正确的说法是：
when(registry.getHandlerFor (route)).thenReturn(handler)
