访问OCMock的andDo中的参数时的EXC_BAD_ACCESS [英] EXC_BAD_ACCESS when accessing parameters in andDo of OCMock

问题描述

我正在尝试使用OCMock的stub 和Do 方法编写一个代码块。

I am trying to write an block of code using OCMock's stub andDo method.

在这种情况下，正在测试UIImageView扩展类。我想检查扩展名是否使用非零参数调用 [self setImage：] （稍后将使用其他图像比较）。

In this case UIImageView extension class is being tested. I want to check that the extension calls [self setImage:] with parameter that is non-nil (later other image comparison will be used).

使用OCMock的和Do 方法时，在块完成后，测试会以EXC_BAD_ACCESS崩溃。

When using OCMock's andDo method, the test crashes with EXC_BAD_ACCESS after the block completes.

id mockView = [OCMockObject mockForClass:[UIImageView class]];
[[[mockView stub] andDo:^(NSInvocation *invocation)
  {
      UIImage *img;
      [invocation getArgument:&img atIndex:2]; <---- line causing the exception
      somebodySetImage |= (img != nil);

  }] setImage:OCMOCK_ANY];

  [mockView do_something_that_calls_setImage];

我现在找到的唯一解决方案是使用 andCall 代替of andDo ，但这会使测试变得复杂。

The only solution that I've found for now is using andCall instead of andDo, but this complicates the test.

我可以使用 andDo 来避免崩溃吗？

Can I avoid the crash with andDo?

UPDATE
好​​吧，我会尝试在这里给出一个更好的例子：
这是测试代码的新部分：

UPDATE Well, I will try to give a better example here: Here is the new piece of the test code:

- (void)testDownloadingThumbnail
{
    PInfo *_sut = [[PInfo alloc] init];

    __block id target = nil;

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

    [[[mock expect] andDo:^(NSInvocation *inv)
    {
        NSInvocationOperation *op;
        [inv getArgument:&op atIndex:2];
        target = [[op invocation] target]; /* replacing this line with STAssert does not help either */
    }] addOperation:OCMOCK_ANY];

    [_sut setDownloadQueue:mock];
    [_sut startDownloadingImagesAsync:YES];

    [mock verify];

    STAssertEqualObjects(target, _sut, @"invalid op target");
}

这是经过测试的代码（PInfo的单一方法）：

Here is the tested code (single method from PInfo):

- (void)startDownloadingImagesAsync:(bool)isThumbnailImg
{
    NSInvocationOperation *inv;

    inv = [[NSInvocationOperation alloc] initWithTarget:self
                                     selector:@selector(loadThumbnailWorker:)
                                       object:nil];
    [[self downloadQueue] addOperation:inv];
}

从 startDownloadingImagesAsync 退出时代码仍然崩溃EXC_BAD_ACCESS。
如果我在 andDo 块中添加一个断点，我看到控件到达这一点并通过 getArgument 检索正确的对象。

The code still crashes upon exit from startDownloadingImagesAsync with EXC_BAD_ACCESS. If I add a breakpoint inside the andDo block, I see that the control reaches this point and retrieves correct objects via getArgument.

然而，如果我在块中使用 getArgument ，它会崩溃我试图做的事情。

Yet, if I use getArgument inside the block, it crashes whatever I try to do.

PS感谢您的帮助。

推荐答案

使用NSProxy的forwardInvocation：方法时遇到了类似的问题。

I ran into a similar problem when using NSProxy's forwardInvocation: method.

你能试试下面的吗？

NSInvocationOperation *op; // Change this line
__unsafe_unretained NSInvocationOperation *op; // to this line

或者另一种方法可能是保留NSInvocation的参数：

Or another approach could be to retain NSInvocation's arguments:

[invocation retainArguments];

http://developer.apple.com/library/ios/documentation/ Cocoa / Reference / Foundation / Classes / NSInvocation_Class / Reference / Reference.html＃// apple_ref / occ / instm / NSInvocation / retainArguments

我会尝试稍后添加更详细的解释。

I'll try to add a more detailed explanation later.

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