ios - 使用 OCMock 模拟 [[UIDevice currentDevice] userInterfaceIdiom]

Question

我正在学习在单元测试中使用 OCMocks，并且我了解基础知识。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(但有效)的接口(interface)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

模拟单例是很棘手的。你可以用一些运行时魔法来做到这一点。可以在 Matt Gallagher's invokeSupersequent macro 的帮助下完成.基本上，您将一个类别添加到您的测试用例中，该类别会覆盖 currentDevice。返回一个模拟，只有当你设置了模拟。这是设置:

#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];
}

我做了一个 more detailed write-up of this approach一会儿回来。