Why does this test fail?
Create a new swift iOS project in XCode 7 called Example with UI tests.
Example/ViewController.swift:
import UIKit
class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        UIPasteboard.generalPasteboard().string = "test"
    }
}
ExampleUITests/ExampleUITests.swift:
import XCTest
class ExampleUITests: XCTestCase {
    override func setUp() {
        super.setUp()
        continueAfterFailure = false
        XCUIApplication().launch()
    }
    override func tearDown() {
        super.tearDown()
    }
    func testExample() {
        XCTAssertNotNil(UIPasteboard.generalPasteboard().string) //this fails
    }
}