如何让ARC下的OCMock停止使用弱属性来设置NSProxy子类？

Question

在ARC,我有一个对象,Child有一个weak属性,parent.我正在尝试编写一些测试Child,并且我正在parent使用它来嘲弄它的属性OCMock.

在ARC下,NSProxy使用合成的弱属性设置器设置子类不会设置属性...设置弱属性后的行,检查它显示它已经存在nil.这是具体的例子:

@interface Child : NSObject
@property (nonatomic, weak) id <ParentInterface>parent;
@end

@implementation Child
@synthesize parent = parent_;
@end

//  ... later, inside a test class ...

- (void)testParentExists
{
    // `mockForProtocol` returns an `NSProxy` subclass
    //
    OCMockObject *aParent = [OCMockObject mockForProtocol:@protocol(ParentInterface)];
    assertThat(aParent, notNilValue());

    // `Child` is the class under test
    //
    Child *child = [[Child alloc] init];
    assertThat(child, notNilValue());

    assertThat(child.parent, nilValue());
    child.parent = (id<ParentInterface>)aParent;
    assertThat([child parent], notNilValue());  // <-- This assertion fails
    [aParent self]; // <-- Added this reference just to ensure `aParent` was valid until the end of the test.
}

我知道我可以使用一个assign属性而不是一个weak属性Child来引用它Parent,但是当我完成它(就像某种穴居人)时我就不得不nil出去了parent,这就是那种ARC应该避免的事情.

有关如何在不更改应用程序代码的情况下通过此测试的任何建议？

编辑:它似乎与OCMockObject成为一个NSProxy,如果我aParent成为一个实例NSObject,child.parent弱引用"保持"非零值.仍在寻找一种方法来使这个测试通过,而无需更改应用程序代码.

编辑2:在接受Blake的回答之后,我在我的预处理器宏项目中做了一个实现,它有条件地将我的属性从weak - > assign改变了.你的旅费可能会改变:

#if __has_feature(objc_arc)
#define BBE_WEAK_PROPERTY(type, name) @property (weak, nonatomic) type name
#else
#define BBE_WEAK_PROPERTY(type, name) @property (assign, nonatomic) type name
#endif

Answer 1

我们一直在努力解决这个问题,它确实与ARC和NSProxy派生对象的弱引用之间的不兼容性有关.我建议使用预处理器指令有条件地编译弱委托引用以在测试套件中分配,以便您可以通过OCMock测试它们.

Answer 2

我找到了一个不同于条件宏的解决方案,因为我正在测试无法更改代码的代码.

我编写了一个简单的类,它扩展了NSObject,而不是NSProxy,它将所有选择器调用转发到OCMockProxy.

CCWeakMockProxy.h:

#import <Foundation/Foundation.h>

/**
 * This class is a hack around the fact that ARC weak references are immediately nil'd if the referent is an NSProxy
 * See: http://stackoverflow.com/questions/9104544/how-can-i-get-ocmock-under-arc-to-stop-nilling-an-nsproxy-subclass-set-using-a-w
 */
@interface CCWeakMockProxy : NSObject

@property (strong, nonatomic) id mock;

- (id)initWithMock:(id)mockObj;

+ (id)mockForClass:(Class)aClass;
+ (id)mockForProtocol:(Protocol *)aProtocol;
+ (id)niceMockForClass:(Class)aClass;
+ (id)niceMockForProtocol:(Protocol *)aProtocol;
+ (id)observerMock;
+ (id)partialMockForObject:(NSObject *)anObject;

@end

CCWeakMockProxy.m:

#import "CCWeakMockProxy.h"
#import <OCMock/OCMock.h>


#pragma mark Implementation
@implementation CCWeakMockProxy

#pragma mark Properties
@synthesize mock;

#pragma mark Memory Management
- (id)initWithMock:(id)mockObj {
    if (self = [super init]) {
        self.mock = mockObj;
    }
    return self;
}

#pragma mark NSObject
- (id)forwardingTargetForSelector:(SEL)aSelector {
    return self.mock;
}

- (BOOL)respondsToSelector:(SEL)aSelector {
    return [self.mock respondsToSelector:aSelector];
}

#pragma mark Public Methods
+ (id)mockForClass:(Class)aClass {
    return [[CCWeakMockProxy alloc] initWithMock:[OCMockObject mockForClass:aClass]];
}

+ (id)mockForProtocol:(Protocol *)aProtocol {
    return [[CCWeakMockProxy alloc] initWithMock:[OCMockObject mockForProtocol:aProtocol]];
}

+ (id)niceMockForClass:(Class)aClass {
    return [[CCWeakMockProxy alloc] initWithMock:[OCMockObject niceMockForClass:aClass]];
}

+ (id)niceMockForProtocol:(Protocol *)aProtocol {
    return [[CCWeakMockProxy alloc] initWithMock:[OCMockObject niceMockForProtocol:aProtocol]];
}

+ (id)observerMock {
    return [[CCWeakMockProxy alloc] initWithMock:[OCMockObject observerMock]];
}

+ (id)partialMockForObject:(NSObject *)anObject {
    return [[CCWeakMockProxy alloc] initWithMock:[OCMockObject partialMockForObject:anObject]];
}

@end

只需使用生成的对象,就像使用常规的OCMockObject一样!