Objective c NSString类型的属性何时为[NSNull null]
我正在解析一些json以返回基本字符串标记或错误消息Objective c NSString类型的属性何时为[NSNull null],objective-c,ocunit,ocmock,nsnull,Objective C,Ocunit,Ocmock,Nsnull,我正在解析一些json以返回基本字符串标记或错误消息 - (void)callBackWithVerifyHttpResponse:(NSData *)response { SomeResult *result = [self.parser parseVerifyHttpResponseAndReturnResult:response]; if (result.token) { [self.delegate callBackWithToken:result.token]; }
- (void)callBackWithVerifyHttpResponse:(NSData *)response
{
SomeResult *result = [self.parser parseVerifyHttpResponseAndReturnResult:response];
if (result.token) { [self.delegate callBackWithToken:result.token]; }
if (result.error) { [self.delegate callBackWithError:result.error]; }
}
证明这一点的测试
- (void)testVerifyCallbackInvokesErrorCallbackOnDelegateWhenParserReturnsError
{
SomeResult *result = [[SomeResult alloc] init];
result.error = @"fail";
[[self.delegate expect] callBackWithError:@"fail"];
[[self.delegate reject] callBackWithToken:OCMArg.any];
[[[self.parser stub] andReturn:result] parseVerifyHttpResponseAndReturnResult:nil];
[self.sut callBackWithVerifyHttpResponse:nil];
[self.delegate verify];
}
- (void)testVerifyCallbackInvokesTokenCallbackOnDelegateWhenParserReturnsToken
{
SomeResult *result = [[SomeResult alloc] init];
result.token = @"token";
[[self.delegate expect] callBackWithToken:@"token"];
[[self.delegate reject] callBackWithError:OCMArg.any];
[[[self.parser stub] andReturn:result] parseVerifyHttpResponseAndReturnResult:nil];
[self.sut callBackWithVerifyHttpResponse:nil];
[self.delegate verify];
}
一切都很好,直到我把它连接到一个实际的端点——结果发现,除非我像下面那样修改回调——它调用了两个回调(不是我所希望的)
第二部分问题
!=[NSNull null]
(但是当我在模拟器中运行时记录值时,我似乎只能得到
@interface SomeResult : NSObject
@property (strong, nonatomic) NSString *token;
@property (strong, nonatomic) NSString *error;
@end
您的原始代码和测试期望令牌或错误为
nil
,而不是[NSNull null]
。当您针对生产端点运行它时,您的解析器可能正在将值设置为[NSNull null]
这些测试应与修改后的代码一起通过:
- (void)testVerifyCallbackInvokesErrorCallbackOnDelegateWhenParserReturnsError
{
SomeResult *result = [[SomeResult alloc] init];
result.error = @"fail";
result.token = [NSNull null];
[[self.delegate expect] callBackWithError:@"fail"];
[[self.delegate reject] callBackWithToken:OCMArg.any];
[[[self.parser stub] andReturn:result] parseVerifyHttpResponseAndReturnResult:nil];
[self.sut callBackWithVerifyHttpResponse:nil];
[self.delegate verify];
}
- (void)testVerifyCallbackInvokesTokenCallbackOnDelegateWhenParserReturnsToken
{
SomeResult *result = [[SomeResult alloc] init];
result.token = @"token";
result.error = [NSNull null];
[[self.delegate expect] callBackWithToken:@"token"];
[[self.delegate reject] callBackWithError:OCMArg.any];
[[[self.parser stub] andReturn:result] parseVerifyHttpResponseAndReturnResult:nil];
[self.sut callBackWithVerifyHttpResponse:nil];
[self.delegate verify];
}
当您处理的web服务和/或第三方解析器可能会微妙地改变其行为时,最好采用防御性编码。您可以同时处理nil
和NSNull
:
- (void)callBackWithVerifyHttpResponse:(NSData *)response
{
SomeResult *result = [self.parser parseVerifyHttpResponseAndReturnResult:response];
if (result.token && result.token != [NSNull null]) { [self.delegate callBackWithToken:result.token]; }
if (result.error && result.error != [NSNull null]) { [self.delegate callBackWithError:result.error]; }
}
您可能还希望将此设置为if/else——首先测试错误,如果出现错误,则永远不要设置令牌,或者如果获得令牌,则忽略错误。如果您不想同时调用这两个回调,则在代码路径中设置为不可能
- (void)callBackWithVerifyHttpResponse:(NSData *)response
{
SomeResult *result = [self.parser parseVerifyHttpResponseAndReturnResult:response];
if (result.token && result.token != [NSNull null]) { [self.delegate callBackWithToken:result.token]; }
if (result.error && result.error != [NSNull null]) { [self.delegate callBackWithError:result.error]; }
}