ios - OCMock:如何 stub -[NSString stringWithContentsOfURL:encoding:error:]

Question

我已经尝试了很多东西。这仍然不起作用:

 id stringMock = OCMClassMock([NSString class]);

 [[[[stringMock stub] ignoringNonObjectArgs] stringWithContentsOfURL:[OCMArg anyPointer] encoding:NSUTF8StringEncoding error:(NSError * __autoreleasing *)[OCMArg anyPointer]] andReturn:stringFromFile];

如何让 -[NSString stringWithContentsOfURL:encoding:error:] 在我的代码中的任何位置返回 stringFromFile？

Answer 1

很遗憾，这是不可能的。

来自 OCMock documentation关于限制(第 10 节):

10.5 Class methods on NSString cannot be stubbed or verified

id stringMock = OCMClassMock([NSString class]); // the following will not work OCMStub([stringMock stringWithContentsOfFile:[OCMArg any] encoding:NSUTF8StringEncoding error:[OCMArg setTo:nil]]);

It is not possible to stub or verify class methods on NSString. Trying to do so has no effect.

但是，您可以包装 NSString 并模拟包装器。这意味着您需要用这个包装器替换代码中的所有调用，但测试会起作用..

这是一个例子:

包装器:

@interface NSStringWrapper : NSObject
+ (nullable id)stringWithContentsOfURL:(NSURL *)url;
@end

@implementation NSStringWrapper
+ (nullable id)stringWithContentsOfURL:(NSURL *)url
{
    return [NSString stringWithContentsOfURL:url];
}
@end

测试:

static NSString *stringFromFile = @"myStringFromFile";

-(void)testStringWrapper
{
    id nsstringWrapperMock = OCMClassMock([NSStringWrapper class]);
    OCMStub(ClassMethod([nsstringWrapperMock stringWithContentsOfURL:OCMOCK_ANY])).andDo(^(NSInvocation *invocation)
    {
      [invocation setReturnValue:&stringFromFile];
    });
    
    NSURL *fakeURL = [NSURL URLWithString:@"htttp://google.com"];
    NSString *test = [NSStringWrapper stringWithContentsOfURL:fakeURL];
    XCTAssertEqual(test, stringFromFile, @"Should always return stringFromFile");
}