使用OCMock模拟[[UIDevice currentDevice] userInterfaceIdiom]

Question

我正在学习如何在单元测试中使用OCMocks，并且我理解其中的基础知识。但是，我不确定如何模拟对类方法的调用。

我想要：

[[UIDevice currentDevice] userInterfaceIdiom]

为我的测试用例返回不同的(但有效的)接口习惯用法。

id mock = [OCMockObject mockForClass:[UIDevice class]];

// Would I use a mock or a stub to have UIDevice mock return
// currentDevice and then from it, return userInterfaceIdiom

Answer 1

模仿单例是一件棘手的事情。您可以使用一些运行时魔术来完成此操作。在Matt Gallagher's invokeSupersequent macro的帮助下，这是可能的。基本上，您可以向测试用例中添加一个覆盖currentDevice以返回模拟的类别，但前提是您设置了模拟。下面是设置：

#import "NSObject+SupersequentImplementation.h"

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wobjc-protocol-method-implementation"

@implementation UIDevice (UnitTests)

+(id)currentDevice {
    if ([BaseTestCase mockDevice]) {
        return [BaseTestCase mockDevice];
    }

    return invokeSupersequentNoArgs();
}

@end

#pragma clang diagnostic pop


static id mockDevice = nil;

+(id)mockDevice {
    return mockDevice;
}

+(id)createMockDevice {
    mockDevice = [OCMockObject mockForClass:[UIDevice class]];
    return mockDevice;
}

+(id)createNiceMockDevice {
    mockDevice = [OCMockObject niceMockForClass:[UIDevice class]];
    return mockDevice;
}

-(void)tearDown {
    mockDevice = nil;
    [super tearDown];
}

然后，在您的测试中：

-(void)testShouldDoSomethingOnIpad {
    id mockDevice = [BaseTestCase createNiceMockDevice];
    [[[mockDevice stub] andReturnValue:OCMOCK_VALUE(UIUserInterfaceIdiomPad)] userInterfaceIdiom];

    // do something iPad-specific

    [mockDevice verify];
}

前段时间我做了一个more detailed write-up of this approach。

Answer 2

这里有一个简单的解决方案：

OCMockObject* _deviceMock = OCMPartialMock([UIDevice currentDevice]);

[[[_deviceMock stub] andReturnValue:@(UIUserInterfaceIdiomPad)] userInterfaceIdiom];

只需确保行为中的代码使用此检查

[UIDevice currentDevice].userInterfaceIdiom

而不是宏

UI_USER_INTERFACE_IDIOM()

Answer 3

另一种方法是将这两种变体都放入您的测试中，并在iPhone和iPad模拟器中运行测试。诚然，这有点麻烦。

-(void)testShouldDoSomething {
    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad) {
        // test iPad behavior
    } else {
        // test iPhone behavior
    }
}