OCMock 在被测代码中自动使用模拟实例? [英] OCMock automatically use mocked instance in code under test?

问题描述

我是 OCMock 的新手.

我使用 dispatch_once() 创建了一个单例类 MyManager :

@implementation MyManager+ (id)sharedInstance {静态 MyManager *sharedMyManager = nil;静态 dispatch_once_t onceToken；dispatch_once(&onceToken, ^{sharedMyManager = [[self alloc] init];});返回 sharedMyManager;}

我在 School 类中有一个使用上述单例的方法:

@实施学校...- (void) createLecture {MyManager *mgr = [MyManager sharedInstance];[经理检查讲座];...}@结尾

现在，我想对这个方法进行单元测试，我使用了 MyManager 的部分模拟:

- (void) testCreateLecture {//创建一个部分模拟的 MyManager 实例id partialMockMgr = [OCMockObject partialMockForObject:[MyManager sharedInstance]];//运行方法进行测试[schoolToTest createLecture];...}

我注意到使用 OCMock，在我创建了我的单例 MyManager 实例的部分模拟之后，当我在测试中运行我的方法时，它自动使用部分模拟的实例.

这对我来说有点奇怪，因为在我上面的测试用例中，我只创建了 MyManager 实例的部分模拟，而没有将它注入到 MyManager 类中，

在被测代码中调用[MyManager sharedInstance]时，OCMock如何自动强制被测代码使用这个模拟实例?有人可以向我解释一下吗?

解决方案

partialMockForObject 模拟您传递给它的对象.

在这种情况下，您正在模拟单例(共享)对象.你不必注入任何东西，因为 sharedInstance 总是返回相同的对象，现在被嘲笑.它仍然是相同的参考.

将部分模拟想象成对传递对象的简单修改，它不会创建新实例，因此您不必在这种特定情况下注入它.

I am new in OCMock.

I use dispatch_once() created a singleton class MyManager :

@implementation MyManager

+ (id)sharedInstance {
    static MyManager *sharedMyManager = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        sharedMyManager = [[self alloc] init];
    });
    return sharedMyManager;
}

I have a method in School class which uses the above singleton:

@implementation School
...
- (void) createLecture {
  MyManager *mgr = [MyManager sharedInstance];
  [mgr checkLectures];
  ...
}
@end

Now, I want to unit test this method, I use a partial mock of MyManager:

- (void) testCreateLecture {
  // create a partially mocked instance of MyManager
  id partialMockMgr = [OCMockObject partialMockForObject:[MyManager sharedInstance]];

  // run method to test
  [schoolToTest createLecture];
  ...
}

I noticed that with OCMock, after I created the partial mock of my singleton MyManager instance, when run my method under test, it automatically use the partially mocked instance.

This is a bit weird to me, since in my test case above, I only created the partial mock of MyManager instance without injecting it to MyManager class,

how does OCMock automatically force the code under test use this mocked instance when [MyManager sharedInstance] is called in the code under test ? Could someone explain to me this?

解决方案

partialMockForObject mocks the object you are passing to it.

In this case you are mocking the singleton (shared) object. You don't have to inject anything because sharedInstance is always returning the same object, now mocked. It is still the same reference.

Imagine partial mocking as a simple mutation of the passed object, it doesn't create a new instance so you don't have to inject it in this specific case.

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