Incrementor

gistfile1.txt

protocol IncrementorInterface {
    func getNumber() -> Int
    func incrementNumber()
    func setMaximumValue(maximumValue: Int)
}

class Incrementor: IncrementorInterface {
    
    var number = 0 {
        didSet {
            // MARK: - check if maxNumber 0
            if maxNumber == 0 {
                number = 0
            }
        }
    }
    
    var maxNumber = Int.max
    
    // MARK: - get current number, default 0
    func getNumber() -> Int {
        return number
    }
    
    // MARK: - increment current number by 1
    func incrementNumber() {
        number += 1
        
        if number == maxNumber {
            number = 0
        }
    }
    
    // MARK: - set value for maximum number, default Int.max
    func setMaximumValue(maximumValue: Int) {
        guard maximumValue >= 0 else { return }
        
        if maximumValue > number {
            number = 0
        }
        
        maxNumber = maximumValue
    }
}

import XCTest

class IncrementorTests: XCTestCase {
    var incrementor: Incrementor!
    
    override func setUp() {
        super.setUp()
        
        incrementor = Incrementor()
    }
    
    override func tearDown() {
        incrementor = nil
        
        super.tearDown()
    }
    
    func testGetCurrentNumber() {
        XCTAssertEqual(incrementor.getNumber(), incrementor.number, "Current number")
    }
    
    func testIncrementNumberByOne() {
        
        incrementor.number = 0
        incrementor.incrementNumber()
        
        XCTAssertEqual(incrementor.getNumber(), 1, "Number increment by 1")
    }
    
    func testSetMaximumValueToTwo() {
        let maxValue = 2
        
        incrementor.number = 0
        incrementor.setMaximumValue(maximumValue: maxValue)
        incrementor.incrementNumber()
        incrementor.incrementNumber()
        
        XCTAssertEqual(incrementor.getNumber(), 0, "Number increment by 2")
    }
    
    func testSetMaximumValueToZero() {
        let maxValue = 0
        
        incrementor.number = 0
        incrementor.setMaximumValue(maximumValue: maxValue)
        incrementor.incrementNumber()
        
        XCTAssertEqual(incrementor.getNumber(), 0, "Number 0 when maxValue 0")
    }
    
    func testSetMaximumValueTonNegative() {
        let maxValue = -1
        
        incrementor.number = 0
        incrementor.maxNumber = Int.max
        incrementor.setMaximumValue(maximumValue: maxValue)
        
        XCTAssertEqual(incrementor.maxNumber, Int.max, "Max value can't be negative")
    }
}