强制删除使用dispatch_once创建的测试代码中的单例 [英] Force deletion of singleton in test code that was created with dispatch_once

问题描述

我正在为模型类编写一些单元测试代码，并希望在应用程序退出和重新启动期间模拟该类的行为.我可以通过删除并重新分配对象来实现此目的，但是它是单例对象，因此以下代码没有达到预期的效果:

I'm writing some unit test code for a model class and want to simulate the behavior of the class during app exit and relaunch. I could achieve this by deleting and re-allocing the object, however its a singleton and thus the following code doesn't have the desired effect:

+ (id) sharedInstance
{
    static MyModel *singleton = nil;
    static dispatch_once_t onceToken;

    dispatch_once(&onceToken, ^ {
        singleton = [[MyModel alloc] initSharedInstance];
    });
    return singleton;
}


// Test code:
    MyModel* gModel = [MyModel sharedInstance];
    ... tests
    gModel = nil;
    gModel = [MyModel sharedInstance];
    ... more tests

是否有一个整洁的解决方案，以便我可以删除/重新创建对象?

Is there a neat solution so I can delete/recreate the object?

推荐答案

static MyModel *singleton = nil;
static dispatch_once_t onceToken;

+ (instancetype) sharedInstance
{
    dispatch_once(&onceToken, ^ {
        if (singleton==nil){
            singleton = [[MyModel alloc] initSharedInstance];
        }
    });
    return singleton;
}

+(void)setSharedInstance:(MyModel *)instance {
    onceToken = 0;
    singleton = instance;
}

没有:

[MyModel setSharedInstance:nil];

请注意，您也可以将其设置为任意类以对其进行模拟.

Note that you can also set it to an arbitrary class to mock it.

[MyModel setSharedInstance:someMock];

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