addUIInterruptionMonitor(withDescription:handler:) not working on iOS 10 or 9

Question

The following tests works fine on iOS 11. It dismisses the alert asking permissions to use the locations services and then zooms in in the map. On iOS 10 or 9, it does none of this and the test still succeeds

func testExample() {
    let app = XCUIApplication()

    var handled = false
    var appeared = false

    let token = addUIInterruptionMonitor(withDescription: "Location") { (alert) -> Bool in
        appeared = true
        let allow = alert.buttons["Allow"]
        if allow.exists {
            allow.tap()
            handled = true
            return true
        }

        return false
    }

    // Interruption won't happen without some kind of action.
    app.tap()

    removeUIInterruptionMonitor(token)
    XCTAssertTrue(appeared && handled)
}

Does anyone have an idea why and/or a workaround?

Here's a project where you can reproduce the issue: https://github.com/TitouanVanBelle/Map

Update

Xcode 9.3 Beta's Changelogs show the following

XCTest UI interruption monitors now work correctly on devices and simulators running iOS 10. (33278282)

Answer 1

let springboard = XCUIApplication(bundleIdentifier: "com.apple.springboard") 

let allowBtn = springboard.buttons["Allow"]
if allowBtn.waitForExistence(timeout: 10) {
    allowBtn.tap()
}

Update .exists to .waitForExistence(timeout: 10), detail please check comments.

Answer 2

I had this problem and River2202's solution worked for me.

Note that this is not a fix to get the UIInterruptionMonitor to work, but a different way of dismissing the alert. You may as well remove the addUIInterruptionMonitor setup. You'll need to have the springboard.buttons["Allow"].exists test anywhere the permission alert could appear. If possible, force it to appear at an early stage of the testing so you don't need to worry about it again later.

Happily the springboard.buttons["Allow"].exists code still works in iOS 11, so you can have a single code path and not have to do one thing for iOS 10 and another for iOS 11.

Incidentally, I logged the base issue (that addUIInterruptionMonitor is not working pre-iOS 11) as a bug with Apple. It has been closed as a duplicate now, so I guess they acknowledge that it is a bug.

Answer 3

I used the @River2202 solution and it works better than the interruption one. If you decide to use that, I strongly suggest that you use a waiter function. I created this one in order to wait on any kind of XCUIElement to appear:

Try it!

// function to wait for an ui element to appear on screen, with a default wait time of 20 seconds
// XCTWaiter was introduced after Xcode 8.3, which is handling better the timewait, it's not failing the test.  It uses an enum which returns: 'Waiters can be used with or without a delegate to respond to events such as completion, timeout, or invalid  expectation fulfilment.'
@discardableResult
func uiElementExists(for element: XCUIElement, timeout: TimeInterval = 20) -> Bool {
    let expectation = XCTNSPredicateExpectation(predicate: NSPredicate(format: "exists == true"), object: element)
    let result = XCTWaiter().wait(for: [expectation], timeout: timeout)
    guard result == .completed else {
        return false
    }
    return true
}