ER: Don't start NSApplication when injecting tests into a dependent target

Number:rdar://7333645 Date Originated:24-Oct-2009 11:43 AM
Status:Open Resolved:
Product:Developer Tools Product Version:Xcode 3.2
Classification:Enhancement Reproducible:N/A
24-Oct-2009 11:43 AM Dave Dribin:
When running a unit test bundle against a GUI application, the test bundle gets injected into the application, and the the tests are run after a delayed performSelector or something.  This means that a lot of the NSApplication startup machinery is still run:

  * The main window NIB is loaded
  * All -awakeFromNib methods are called
  * -applicationWillFinishLaunching: is called

While this can be useful if you are doing higher-level integration testing, this is not good for true low-level unit testing where you are testing individual classes in isolation:


First off, it slows down the tests by loading the NIB and running code that does not affect the tests.  Worse is -awakeFromNib or -applicationWillFinishLaunching: may adversely interfere with tests by kicking off timers and background threads or registering for notifications.  They could even block app startup by showing a modal window.

I once had to add code that skipped part of app initialization if it was being run under OCUnit (by checking for the existence of the SenTestCase class).  This is a code smell due to putting test logic in production code:


I've gotten around the problem altogether by replacing main() with the following code.  However, it would be nice if this was built into the default NSApplicationMain machinery somehow.

#import <Cocoa/Cocoa.h>

int DDTestApplicationMain(int argc, const char ** argv)
    BOOL testMode = (getenv("TEST_HOST") != NULL);
    if (!testMode) {
        return NSApplicationMain(argc, argv);
    } else {
        [[NSRunLoop currentRunLoop] run];
        return 0;

int main(int argc, char *argv[])
    return DDTestApplicationMain(argc, (const char **)argv);


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