How to let the app know if it's running Unit tests in a pure Swift project?

Question

One annoying thing when running tests in Xcode 6.1 is that the entire app has to run and launch its storyboard and root view controller. In my app this runs some server calls th

Answer 1

Elvind's answer isn't bad if you want to have what used to be called pure "Logic Tests". If you'd still like to run your containing host application yet conditionally execute or not execute code depending on whether tests are run, you can use the following to detect if a test bundle has been injected:

if NSProcessInfo.processInfo().environment["XCTestConfigurationFilePath"] != nil {
     // Code only executes when tests are running
}

I used a conditional compilation flag as described in this answer so that the runtime cost is only incurred in debug builds:

#if DEBUG
    if NSProcessInfo.processInfo().environment["XCTestConfigurationFilePath"] != nil {
        // Code only executes when tests are running
    }
#endif

Edit Swift 3.0

if ProcessInfo.processInfo.environment["XCTestConfigurationFilePath"] != nil {
    // Code only executes when tests are running
}

Answer 2

First add variable for testing:

and use that in your code:

 if ProcessInfo.processInfo.environment["IS_UNIT_TESTING"] == "1" {
                 // Code only executes when tests are running
 } 

Answer 3

Apparently in Xcode12 we need to search in the environment key XCTestBundlePath instead of XCTestConfigurationFilePath if you are using the new XCTestPlan

Answer 4

I use this in application:didFinishLaunchingWithOptions:

// Return if this is a unit test
if let _ = NSClassFromString("XCTest") {
    return true
}

Answer 5

Worked for me:

Objective-C

[[NSProcessInfo processInfo].environment[@"DYLD_INSERT_LIBRARIES"] containsString:@"libXCTTargetBootstrapInject"]

Swift: ProcessInfo.processInfo.environment["DYLD_INSERT_LIBRARIES"]?.contains("libXCTTargetBootstrapInject") ?? false

Answer 6

var isRunningTests: Bool {
    return ProcessInfo.processInfo.environment["XCTestConfigurationFilePath"] != nil
}

Usage

if isRunningTests {
    return "lena.bmp"
}
return "facebook_profile_photo.bmp"