Open Radar

 
Summary:
Subclassing XCTestLog to modify the information logged during a test run will result in Xcode displaying false information about the test run. 

Steps to Reproduce:
1. Add a subclass of XCTestLog to your test target
2. Override -testLogWithFormat:arguments: and change the format of the log data before writing to the log file handle.
For example:

#import "RedGreenXCTestLog.h"

NSString *const kXCTTestCaseArgsFormat = @"%@|%s|%.3f";
NSString *const kRGArgsSeparator = @"|";
NSString *const kRGTestCaseFinishFormat = @"Test Case '%@' %s (%.3f seconds).\n";
NSString *const kRGModifiedTestResultFormat = @"%@: %@ (%@s)\n";

@implementation RedGreenXCTestLog

+ (void)load
{
    [[NSUserDefaults standardUserDefaults] setValue:NSStringFromClass(self)
                                             forKey:XCTestObserverClassKey];
}

- (void)testLogWithFormat:(NSString *)format arguments:(va_list)arguments
{
    if (![format isEqualToString:kRGTestCaseFinishFormat]) {
        return;
    }
    
    // Produce output in the form "<RESULT>: <test case> (duration)"
    NSArray *args = NSArrayFromArguments(arguments);
    NSString *formattedLog = [NSString stringWithFormat:kRGModifiedTestResultFormat, [args[1] uppercaseString], args[0], args[2]];
    
    [self.logFileHandle writeData:[formattedLog dataUsingEncoding:NSUTF8StringEncoding]];
}

NSArray *NSArrayFromArguments(va_list arguments)
{
    NSString *s = [[NSString alloc] initWithFormat:kXCTTestCaseArgsFormat arguments:arguments];
    NSArray *args = [s componentsSeparatedByString:kRGArgsSeparator];
    
    return args;
}

@end

3. Write a few tests that will only succeed. 
4. Run the test suite

Expected Results:
Xcode will display a Test Passed HUD, the Test Navigator & the Log Navigator will show that all tests passed. 

Actual Results:
Xcode displays a Test Failed HUD and the Log Navigator displays a warning that the test target did not finish. The Test Navigator correctly shows all tests as having passed.