ios - 如何模拟符合协议(protocol)并被 OCMock 模拟的对象的属性？

Question

我正在按照 Test driven iOS Development 中的示例进行操作在一种情况下，有一个单元测试可确保委托(delegate)获得错误方法的“简化”版本。因此，这里无需过多介绍相关对象:

• communicator:负责进行网络调用的对象
• ma​​nager:指示 communicator 进行调用，然后将结果推送给它的 delegate。
• delegate: 符合 StackOverflowManagerDelegate 协议(protocol)的管理器委托(delegate)。获取结果并对其进行处理。

所以这就是测试:

@implementation QuestionCreationTests

{
    @private
    StackOverflowManager *mgr;
}
- (void)testErrorReturnedToDelegateIsNotErrorNotifiedByCommunicator {
    MockStackOverflowManagerDelegate *delegate =
    [[MockStackOverflowManagerDelegate alloc] init];
    mgr.delegate = delegate;
    NSError *underlyingError = [NSError errorWithDomain: @"Test domain"
                                                   code: 0 userInfo: nil];
    [mgr searchingForQuestionsFailedWithError: underlyingError];
    XCTAssertFalse(underlyingError == [delegate fetchError],
                  @"Error should be at the correct level of abstraction");
}

这是 StackOverflowManager 中 searchingForQuestionsFailedWithError 的实现，其中管理器简单地简化了通信器返回的原始错误，并将简化后的版本发送给委托(delegate)。

- (void)searchingForQuestionsFailedWithError:(NSError *)error {
    NSDictionary *errorInfo = [NSDictionary dictionaryWithObject: error
                                                          forKey: NSUnderlyingErrorKey];
    NSError *reportableError = [NSError
                                errorWithDomain: StackOverflowManagerSearchFailedError
                                code: StackOverflowManagerErrorQuestionSearchCode
                                userInfo:errorInfo];
    [delegate fetchingQuestionsOnTopic: nil
                       failedWithError: reportableError];
}

作者建议为了让这个工作..我们实际上必须像这样为经理委托(delegate)创建一个模拟对象:

@interface MockStackOverflowManagerDelegate : NSObject <StackOverflowManagerDelegate>
@property (strong) NSError *fetchError;

@end

@implementation MockStackOverflowManagerDelegate

@synthesize fetchError;

- (void)fetchingQuestionsOnTopic: (Topic *)topic
                 failedWithError: (NSError *)error {
    self.fetchError = error;
}

@end

这是 StackOverflowManagerDelegate 的声明:

@protocol StackOverflowManagerDelegate <NSObject>    
- (void)fetchingQuestionsOnTopic: (Topic *)topic
                 failedWithError: (NSError *)error {    
@end

---

问题:我一直在浏览本书的所有示例，并尝试使用 OCMock 而不是像作者那样手动制作的示例。(我只是认为这将是一个耗时少很多)。到目前为止一切正常..但我被困在这里..如何在委托(delegate)上伪造一个名为 fetchError 的属性？这是我现在拥有的:

- (void)testErrorReturnedToDelegateIsNotErrorNotifiedByCommunicator {
    id <StackOverflowManagerDelegate> delegate = 
       [OCMockObject mockForProtocol:@protocol(StackOverflowManagerDelegate)];
    mgr.delegate = delegate;

    NSError *underlyingError = [NSError errorWithDomain: @"Test domain"
                                                   code: 0 userInfo: nil];

    [mgr searchingForQuestionsFailedWithError: underlyingError];

    // compiler error here: no known instance method for selector 'fetchError'
    XCTAssertFalse(underlyingError == [mgr.delegate fetchError], @"error ");
}

在经理的内心深处，经理在委托(delegate)上调用了fetchingQuestionsOnTopic。我知道我可以通过using伪造那个方法。 [[[delegate stub] andCall:@selector(differentMethod:) onObject:differentObject] fetchingQuestionsOnTopic:[OCMArg any]] 其中 differentMethod 会做我想让它做的任何事情。 . 我只是不知道如何处理 differentMethod 的结果:我不知道如何将它存储在委托(delegate)的模拟属性中。

---

更新:作为下面答案的后续。这里是单元测试的实现，确保底层错误仍然对委托(delegate)可用:

- (void)testErrorReturnedToDelegateDocumentsUnderlyingError {
    MockStackOverflowManagerDelegate *delegate =
    [[MockStackOverflowManagerDelegate alloc] init];
    mgr.delegate = delegate;
    NSError *underlyingError = [NSError errorWithDomain: @"Test domain"
                                                   code: 0 userInfo: nil];
    [mgr searchingForQuestionsFailedWithError: underlyingError];
    XCTAssertEqual([[[delegate fetchError] userInfo]
                          objectForKey: NSUnderlyingErrorKey], underlyingError,
                         @"The underlying error should be available to client code");
}

这是它的 OCMock 版本:

- (void)testErrorReturnedToDelegateDocumentsUnderlyingErrorOCMock {
    id delegate =
    [OCMockObject mockForProtocol:@protocol(StackOverflowManagerDelegate)];
    mgr.delegate = delegate;

    NSError *underlyingError = [NSError errorWithDomain: @"Test domain"
                                                   code: 0 userInfo: nil];

    [[delegate expect] fetchingQuestionsFailedWithError:
       [OCMArg checkWithBlock:^BOOL(id param) {

        return ([[param userInfo] objectForKey:NSUnderlyingErrorKey] == underlyingError);

    }]];

    [mgr searchingForQuestionsFailedWithError: underlyingError];

    [delegate verify];
}

Answer 1

试试这个:

- (void)testErrorReturnedToDelegateIsNotErrorNotifiedByCommunicator {
    id delegate = 
       [OCMockObject mockForProtocol:@protocol(StackOverflowManagerDelegate)];
    mgr.delegate = delegate;

    NSError *underlyingError = [NSError errorWithDomain: @"Test domain"
                                                   code: 0 userInfo: nil];

    [[delegate expect] fetchingQuestionsOnTopic:OCMOCK_ANY 
                                failedWithError:[OCMArg isNotEqual:underlyingError]];

    [mgr searchingForQuestionsFailedWithError:underlyingError];

    [delegate verify];
}

要测试管理器报告的错误的域、代码和用户信息(如果我记得很好的话，这是那本书中的另一个测试用例 - 我很久以前读过)，您可以执行以下操作:

    id <StackOverflowManagerDelegate> delegate = 
       [OCMockObject mockForProtocol:@protocol(StackOverflowManagerDelegate)];
    mgr.delegate = delegate;

    NSError *underlyingError = [NSError errorWithDomain: @"Test domain"
                                                   code: 0 userInfo: nil];

    NSError *expectedError = [NSError errorWithDomain:@"expected domain" 
                                                 code:0/* expected code here*/ 
                                             userInfo:@{NSUnderlyingErrorKey: underlyingError}];
    [[delegate expect] fetchingQuestionsOnTopic:OCMOCK_ANY 
                                failedWithError:expectedError];

    [mgr searchingForQuestionsFailedWithError: underlyingError];

    [delegate verify];