调用[NSBundle mainBundle]时XCTest失败 [英] XCTest fails when calling [NSBundle mainBundle]

问题描述

我有一些代码在某些时候调用 [NSBundle mainBundle] ，主要是读取/设置首选项。当我对方法进行单元测试时，测试失败，因为测试的mainBundle不包含该文件。

I have some code that calls [NSBundle mainBundle] at some point, mainly to read/set preferences. When I unit test the method, the test fails because the test's mainBundle does not contain the file.

这是一个已知的问题，Apple将不会修复，因为他们认为它是不是错误：

This is a known issue, that Apple won't fix as they consider it is not a bug:

他们回复的要点是XCTest正常工作返回它自己的主包而不是测试目标的包。

the gist of their reply is that XCTest is working correctly by returning it’s own main bundle instead of the bundle of the test target.

以前我们的代码库在<$ c $上使用类别覆盖c> NSBundle 的 + mainBundle 类方法来解决这个问题。但这很危险，因为覆盖类别中的现有方法是未定义的。

Previously our codebase was using a category override on NSBundle's +mainBundle class method to work around this. But this is dangerous because the behaviour of overriding an existing method in a category is undefined.

如果在类别中声明的方法的名称与原始类中的方法相同，或者在另一个类别中的方法相同在同一个类（甚至是超类）中，行为未定义为在运行时使用哪个方法实现。

If the name of a method declared in a category is the same as a method in the original class, or a method in another category on the same class (or even a superclass), the behavior is undefined as to which method implementation is used at runtime.

实际上Xcode警告关于它：

Actually Xcode warns you about it:

类别实现的方法也将由其主要类实现

Category is implementing a method which will also be implemented by its primary class

那么，解决这个问题的正确方法是什么？

So, what is the proper method to address the issue?

推荐答案

解决此问题的最简单，最简洁的方法是在单元测试中部分模拟NSBundle类以返回<$ c当你打电话给 [NSBundle mainBundle] 时，$ c> [NSBundle bundleForClass：[self class]] 。

The simplest and cleanest way of fixing this issue is to partially mock the NSBundle class in your unit tests to return [NSBundle bundleForClass:[self class]] when you call [NSBundle mainBundle].

您可以将它放在 -setup 方法中，以便为整个测试类进行模拟：

You may put this in your -setup method so that it is mocked for your entire test class:

static id _mockNSBundle;

@implementation MyTests

- (void)setUp
{
  [super setUp];

  _mockNSBundle = [OCMockObject niceMockForClass:[NSBundle class]];
  NSBundle *correctMainBundle = [NSBundle bundleForClass:self.class];
  [[[[_mockNSBundle stub] classMethod] andReturn:correctMainBundle] mainBundle];
}

@end

干净整洁。

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