Tail Call Optimization test

TCOTests.swift

//
//  TCOTests.swift
//  Playground
//
//  Created by kori on 4/20/16.
//  Copyright © 2016 hiroshi.kori. All rights reserved.
//

import XCTest

func simpleRec(n: Int) -> Int {
    if n == 0 {
        return 0
    } else {
        return 1 + simpleRec(n-1)
    }
}

// vs

func tailRec(n: Int, res: Int = 0) -> Int {
    if n == 0 {
        return res
    } else {
        return tailRec(n - 1, res: res + 1)
    }
}

class TCOTests: XCTestCase {
    let recCount = 1000000
    
    func testTailRec() {
        XCTAssertEqual(tailRec(recCount), recCount)
    }
    
    func testSimpleRec() {
        XCTAssertEqual(simpleRec(recCount), recCount)
    }
}