Swift: How to not load AppDelegate during Tests

Question

I have an OS X application which on startup loads some data from a server and pushes notifications to the NSUserNotificationCenter. Now I have the problem that this also happens during my unit tests. I found no way yet to prevent this. Of course I could stub the HTTP loads. But in some cases I want to test the loading and then the notifications get sent anyway.

What I'm trying to do is to make the test runs not load the AppDelegate but a fake one that I'm only using for tests. I found several examples [1] on how to do that with UIApplicationMain, where you can pass a specific AppDelegate class name. The same is not possible with NSApplicationMain [2].

What I've tried is the following:

Removed @NSApplicationMain from AppDelegate.swift, then added a main.swift with the following content:

class FakeAppDelegate: NSObject, NSApplicationDelegate {
}

NSApplication.sharedApplication()
NSApp.delegate = FakeAppDelegate()
NSApplicationMain(Process.argc, Process.unsafeArgv)

This code runs before tests but has no effect at all.

I might have to say: My AppDelegate is almost empty. To handle the MainMenu.xib stuff I made a separate view controller which does the actual loading and notification stuff in awakeFromNib.

[1] http://www.mokacoding.com/blog/prevent-unit-tests-from-loading-app-delegate-in-swift/

[2] https://developer.apple.com/library/mac/documentation/Cocoa/Reference/ApplicationKit/Miscellaneous/AppKit_Functions/#//apple_ref/c/func/NSApplicationMain

Answer 1

Just an update on the previous accept answer, this is my main.swift:

private func isTestRun() -> Bool {
    return NSClassFromString("XCTestCase") != nil
}

if isTestRun() {
    // This skips setting up the app delegate
    NSApplication.shared.run()
} else {
    // For some magical reason, the AppDelegate is setup when
    // initialized this way
    _ = NSApplicationMain(CommandLine.argc, CommandLine.unsafeArgv)
}

A bit more compact! I'm using Swift 4.1 and XCode 9.4.1