如何创建UIPrintPaper来测试UIPrintInteractionControllerDelegate

问题描述

已经编写了中对它的纸张选择功能进行单元测试。 p>

其声明为：

 可选功能func printInteractionController（_ printInteractionController（_ printInteractionController：UIPrintInteractionController，选择纸张文件列表：[UIPrintPaper]）-> UIPrintPaper 
  

用预定义的UIPrintPaper值调用它并检查输出是一个简单的问题。但是，我无法创建UIPrintPaper实例。 UIPrintPaper的声明方式如下：

  NS_CLASS_AVAILABLE_IOS（4_2）__ TVOS_PROHIBITED @interface UIPrintPaper：NSObject 
 
 + （UIPrintPaper *）bestPaperForPageSize：（CGSize）contentSize withPapersFromArray：（NSArray< UIPrintPaper *> *）paperList; //供委托使用。传入列表
 
 @property（只读）CGSize paperSize; 
 @property（readonly）CGRect printableRect; 
 
 @end 
  

paperSize和printableRect属性为只读，没有初始化程序来定义它们。如何创建UIPrintPaper来代表测试的不同纸张尺寸？ （A4，美国字母，4x6 ...）

解决方案

无法控制UIPrintPaper，但是将其子类化以覆盖其只读属性是直接的：

  class FakePrintPaper：UIPrintPaper {
 
 private let size：CGSize 
得以覆盖var paperSize：CGSize {返回尺寸} 
覆盖var printableRect：CGRect {返回CGRect（来源：CGPointZero，大小：size）} 
 
 init（size：CGSize）{
 self .size =大小
} 
} 
  

Having written a UIPrintInteractionControllerDelegate, I wish to unit test its paper selection functionality in printInteractionController:choosePaper:

Its declaration is:

optional func printInteractionController(_ printInteractionController: UIPrintInteractionController, choosePaper paperList: [UIPrintPaper]) -> UIPrintPaper

It is a simple matter of calling it with predefined UIPrintPaper values and checking the output. However I am unable to create UIPrintPaper instances. Here is how UIPrintPaper is declared:

NS_CLASS_AVAILABLE_IOS(4_2)__TVOS_PROHIBITED @interface UIPrintPaper : NSObject 

+ (UIPrintPaper *)bestPaperForPageSize:(CGSize)contentSize withPapersFromArray:(NSArray<UIPrintPaper *> *)paperList; // for use by delegate. pass in list

@property(readonly) CGSize paperSize;
@property(readonly) CGRect printableRect;

@end

The paperSize and printableRect properties are readonly and there is no initializer to define them. How can I create UIPrintPaper to represent different paper sizes for my tests? (A4, US Letter, 4x6...)

解决方案

Can't control UIPrintPaper, but subclassing it to override its readonly properties is straighforward:

class FakePrintPaper: UIPrintPaper {

    private let size: CGSize
    override var paperSize: CGSize { return size }
    override var printableRect: CGRect  { return CGRect(origin: CGPointZero, size: size) }

    init(size: CGSize) {
        self.size = size
    }
}

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