IOS -NSRunLoop in XCTest: How Do I Get A Run Loop to Work in A Unit Test?

Question

OK. I looked around, and didn\'t find an exact answer to my issue.

I am trying to test a timeout handler in a unit test (not the main run).

The issue seems t

Answer 1

When you use timers and the main runloop, you will need to manually run the runloop:

while (continueCondition || !time_way_over_timeout)  {
    [[NSRunLoop mainRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
}

where continueConditioncould be some flag that indicates that the timeout handler was invoked and time_way_over_timeouta comparision of the current time with a pre-calulated maximum execution time (so you can handle a "timeout of timout test" for your unit test ^^)

Also see this blog post about asynchronous unit testing: http://dadabeatnik.wordpress.com/2013/09/12/xcode-and-asynchronous-unit-testing/

Answer 2

Looks something like this in Swift 3.0 with XCTest.

// somebody has to call the .fulfill() method on this variable 
// to the expectation will fail after 25 seconds
var asyncExpectation : XCTestExpectation!

func testExample() {
    asyncExpectation = expectation(description: "longRunningFunction")
    self.waitForExpectations(timeout: 25.0) { (error) in
        if let error = error {
            print("Error \(error)")
        }
    }
    // more stuff here
}