如何单元测试NSCoding？ [英] How to unit test NSCoding?

问题描述

我有一个iOS应用程序，数据持久使用NSCoding和更准确的NSKeyedArchiver。此应用程序已在App Store上提供。

I have an iOS application with data persisted using NSCoding and more precisely NSKeyedArchiver. This application is already available on the App Store.

我正在使用版本2的应用程序，数据模型应该更改。所以我需要处理数据模型迁移。

I'm working on version 2 of the application and the data model should change. So I need to handle data model migration. I want it covered by unit tests.

在我的测试中，我想使用旧的数据模型动态生成持久化数据，启动迁移并查看一切是否正常

目前，归档对象如下所示：

Currently, archiving an object looks like this :

MyDataModelObject *object = ....
NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
[archiver encodeObject:object forKey:key];
[archiver finishEncoding];

问题是，MyDataModelObject可能在应用程序的版本2中被重新计算甚至删除。所以我不能在测试中使用这个类来生成一个'旧版本的归档'。

The problem is, MyDataModelObject might be re-factored or even deleted in the version 2 of the application. So I can't use this class in my tests to generate an 'old version archive'.

有没有办法模拟在 encodeWithCoder：不使用此类的类的方法

Is there a way to simulate what is done in the encodeWithCoder: method of a class without using this class ?

我想要实现的是以下

- testMigrationFrom_v1_to_v2 {
    // simulate an archive with v1 data model
    // I want this part of the code to be as simple as possible
    // I don't want to rely on old classes to generate the archive
    NSDictionary *person = ... // { firstName: John, lastName: Doe }
    NSDictionary *adress = ... // { street: 1 down street, city: Butterfly City }
    [person setObject:adress forKey:@"adress"];

    // there's something missing to tell the archiever that:
    // - person is of type OldPersonDataModel
    // - adress is of type OldAdressDataModel

    [archiver encodeObject:person forKey:@"somePerson"];
    // at this point, I would like the archive file to contain :
    // a person object of type OldPersonDataModel, that has an adress object of type OldAdressModel 

    NewPersonModel *newPerson =  [Migration readDataFromV1];

    // assertions
    NSAssert(newPerson.firstName, @"John");
    NSAssert(newPerson.lastName, @"Doe");
}

推荐答案

你的问题所以我会给你两个答案：

I don't really understand your question so I will give you two answers:

你可以预先加载一个 NSDictionary

您还可以获取任何类的 -attributeKeys 方法获取所有密钥，然后可能使用此代码来模拟归档：

You can also get any class's -attributeKeys method to get all the keys and then possibly use this code to simulate an archive:

NSKeyedArchiver *archive = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
[archiver encodeObject:object forKey:key];
for (NSString *key in object.attributeKeys) {
    [archive encodeObject:[object valueForKey:key] forKey:key];
}
[archive finishEncoding];

在迁移数据时，NSKeyedArchiver有方法 -setClass：forClassName： ，您可以支持新对象中的所有旧密钥，将其转换为不同的属性。

On the point of migrating data, NSKeyedArchiver has the method -setClass:forClassName: and you can support all of your old keys in your new object to translate them into different properties.

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