import Foundation
import XCTest

extension Collection where Indices.Iterator.Element == Index {
    subscript(safe index: Index) -> Iterator.Element? {
        return indices.contains(index) ? self[index] : nil
    }
}

class PerfomanceTester: XCTestCase {
    let measureIterations = 100_000

    let array: [String] = {
        var array = [String]()
        for _ in 1...10_000 {
            array.append("test")
        }
        return array
    }()

    func testNormal() {
        measure {
            for _ in 1...measureIterations {
                let _ = array[10]
            }
        }
    }

    func testSafe() {
        measure {
            for _ in 1...measureIterations {
                let _ = array[safe: 10]
            }
        }
    }
}

PerfomanceTester.defaultTestSuite.run()