What is the proper way to detect if unit tests are running at runtime in Xcode? - objective-c

Question

When I'm running unit tests, I'd like to skip some code (e.g. I don't want [[UIApplication sharedApplication] openURL:..] to run). I'm looking for a runtime check if I'm currently running units tests or not.
I know I have seen code that checks the Objective-C runtime if unit tests are running but am not able to find it anymore.

Answer 1

You can use this method from google-toolbox-for-mac
// Returns YES if we are currently being unittested.
+ (BOOL)areWeBeingUnitTested {
BOOL answer = NO;
Class testProbeClass;
#if GTM_USING_XCTEST // you may need to change this to reflect which framework are you using
testProbeClass = NSClassFromString(#"XCTestProbe");
#else
testProbeClass = NSClassFromString(#"SenTestProbe");
#endif
if (testProbeClass != Nil) {
// Doing this little dance so we don't actually have to link
// SenTestingKit in
SEL selector = NSSelectorFromString(#"isTesting");
NSMethodSignature *sig = [testProbeClass methodSignatureForSelector:selector];
NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:sig];
[invocation setSelector:selector];
[invocation invokeWithTarget:testProbeClass];
[invocation getReturnValue:&answer];
}
return answer;
}
The reason that NSClassFromString and NSInvocation are used is to allow code compile without linking to xctest or ocunit

Answer 2

Rather that sprinkling "am I testing?" conditionals throughout production code, I isolate the check to one place: main. There, I check for an alternate application delegate for testing. If it's available, I use it instead of the the regular application delegate. This completely bypasses the regular launch sequence:
int main(int argc, char *argv[])
{
#autoreleasepool {
Class appDelegateClass = NSClassFromString(#"TestingAppDelegate");
if (!appDelegateClass)
appDelegateClass = [AppDelegate class];
return UIApplicationMain(argc, argv, nil, NSStringFromClass(appDelegateClass));
}
}
You can read more about this technique here: How to Easily Switch Your iOS App Delegate for Testing

Answer 3

Select the project, and then the test target:
Select Build Settings and choose All and Combined. Type 'preproc' in the search box - you're after Preprocessor Macros.
Add a macro to the Debug configuration called TEST and set it equal to 1:
Then in your code, you can do this:
#ifndef TEST
[[UIApplication sharedApplication] doEvilThingForTesting];
#endif
Or if you have code that you want to only run in a test environment:
#ifdef TEST
[[UIApplication sharedApplication] doAwesomeTestOnlyThing];
#endif
It's not exactly runtime, but the unit tester compiles the code before it runs the tests IIRC, so it should be the same effect - you're essentially modifying the code right before running the tests.

Answer 4

I'm not sure how long this will continue to work, but it works for me right now with Version 9.0 beta 6 (9M214v).
let isTesting = { () -> Bool in
if let _ = ProcessInfo.processInfo.environment["XCTestConfigurationFilePath"] {
return true
} else if let testingEnv = ProcessInfo.processInfo.environment["DYLD_INSERT_LIBRARIES"] {
return testingEnv.contains("libXCTTargetBootstrapInject.dylib")
} else {
return false
}
}()
No build environment or scheme changes are necessary.
It appears that there are two different environment variables in play depending on whether you are running a single test case or the entire test suite. Also, the variable value also differs depending whether or not you are running in simulator or on a real device.

Answer 5

I think you can check like this for Xcode 7.3
-(BOOL) isRunningUnitTests
{
NSDictionary* environment = [ [ NSProcessInfo processInfo ] environment ];
NSString* theTestConfigPath = environment[ #"XCTestConfigurationFilePath" ];
return theTestConfigPath != nil;
}

Answer 6

The easiest (and working in Xcode 7 with XCTest!) way to check is to have a look at the process info for a matching xctest bundle:
static BOOL isRunningTests(void)
{
NSDictionary* environment = [[NSProcessInfo processInfo] environment];
NSString* injectBundle = environment[#"XCInjectBundle"];
return [[injectBundle pathExtension] isEqualToString:#"xctest"];
}
Source: https://www.objc.io/issues/1-view-controllers/testing-view-controllers/#integration-with-xcode

Answer 7

Just use this:
+ (BOOL)isUnitTestRunning
{
Class testProbeClass;
testProbeClass = NSClassFromString(#"XCTestProbe");
return (testProbeClass != nil);
}