为什么我的单元测试中我的对象的弱委托属性为零？ [英] Why is my object's weak delegate property nil in my unit tests?

问题描述

我有一个非常简单的单元测试设置。我有一个具有委托属性的类：

I have a pretty simple setup for this unit test. I have a class that has a delegate property:

@interface MyClass : NSObject
...
@property (nonatomic, weak) id<MyDelegateProtocol> connectionDelegate;
...
@end

我在我的测试中设置了委托：

and I set the delegate in my test:

- (void)testMyMethod_WithDelegate {
  id delegate = mockDelegateHelper(); // uses OCMock to create a mock object
  [[delegate expect] someMethod];
  myClassIvar.connectionDelegate = delegate;
  [myClass someOtherMethod];
  STAssertNoThrow([delegate verify], @"should have called someMethod on delegate.");
}

但代表实际上并未设置在我的单元测试的第3行，所以永远不会调用#someMethod。当我将其更改为

But the delegate is not actually set on line 3 of my unit test, so #someMethod is never called. When I change it to

myClassIvar.connectionDelegate = delegate;
STAssertNotNil(myClassIvar.connectionDelegate, @"delegate should not be nil");

它在那里失败了。我正在使用ARC，所以我的预感是弱房产被解除分配。果然，将其更改为 strong 会使 STAssertNotNil 通过。但是我不想和代表那样做，我不明白为什么这会对你有所作为。根据我的阅读，ARC中的所有本地引用都是 strong ，而 STAssertNotNil（委托）通过。当局部变量中的同一对象不是时，为什么我的弱委托属性为nil？

it fails there. I'm using ARC, so my hunch was that the weak property was being deallocated. Sure enough, changing it to strong makes the STAssertNotNil pass. But I don't want to do that with a delegate, and I don't understand why that makes a difference here. From what I've read, all local references in ARC are strong, and STAssertNotNil(delegate) passes. Why is my weak delegate property nil when the same object in a local variable is not?

推荐答案

这是iOS中的一个错误运行。以下讨论有更多细节。简而言之，iOS ARC运行时似乎无法处理对代理的弱引用。 OSX运行时可以。

This is a bug in the iOS runtime. The following discussion has more detail. In a nutshell, the iOS ARC runtime can't seem to handle weak references to proxies. The OSX runtime can.

http://www.mulle-kybernetik.com/forum/viewtopic.php?f=4&t=252

据我所知，从讨论中已经向Apple提交了一份错误报告。如果有人对解决方法有明智的想法......

As far as I understand from the discussion a bug report has been filed with Apple. If anyone has a sensible idea for a workaround...

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