FizzBuzz.swift

struct FizzBuzz {
    func makeIf(with value: Int) -> String {
        guard value > 0 else { return "" }
        if value % 15 == 0 {
            return "fizzbuzz"
        }
        else if value % 3 == 0 {
            return "fizz"
        }
        else if value % 5 == 0 {
            return "buzz"
        }
        else {
            return String(value)
        }
    }
    
    func make(with value: Int) -> String {
        guard value > 0 else { return "" }
        switch (value % 3, value % 5) {
        case (0, 0): return "fizzbuzz"
        case (0, _): return "fizz"
        case (_, 0): return "buzz"
        case (_, _): return String(value)        }
    }
    
    func fizzbuzz(lines : Int)->Array<String> {
        var result : [String] = []
        guard lines > 0 else { return [] }
        for index in 1...lines {
            result.append(make(with: index))
        }
        return result
    }
}

TestFizzBuzz.swift

//
//  FizzBuzzTest.swift
//  FizzBuzzTest
//
//  Created by JK on 2019/09/18.
//  Copyright © 2019 codesquad. All rights reserved.
//

import XCTest

class FizzBuzzTest: XCTestCase {
    var fb : FizzBuzz! = nil

    override func setUp() {
        fb = FizzBuzz()
    }

    override func tearDown() {
    }

    func test_인스턴스_만들기_성공() {
        XCTAssertNotNil(fb)
    }
    
    func test_0일때_공백출력() {
        let result = fb.make(with: 0)
        XCTAssertEqual(result, "")
    }
    
    func test_1일때_숫자출력() {
        let result = fb.make(with: 1)
        XCTAssertEqual(result, "1")
    }

    func test_3일때_fizz출력() {
        let result = fb.make(with: 3)
        XCTAssertEqual(result, "fizz")
    }
    
    func test_5일때_buzz출력() {
        let result = fb.make(with: 5)
        XCTAssertEqual(result, "buzz")
    }
    
    func test_15일때_fizzbuzz출력() {
        let result = fb.make(with: 15)
        XCTAssertEqual(result, "fizzbuzz")
    }

    func test_3배수일때_fizz출력() {
        let result6 = fb.make(with: 6)
        XCTAssertEqual(result6, "fizz")
        let result9 = fb.make(with: 9)
        XCTAssertEqual(result9, "fizz")
    }
    
    func test_5배수일때_buzz출력() {
        let result10 = fb.make(with: 10)
        XCTAssertEqual(result10, "buzz")
        let result25 = fb.make(with: 25)
        XCTAssertEqual(result25, "buzz")
    }
    
    func test_15배수일때_buzz출력() {
        let result30 = fb.make(with: 30)
        XCTAssertEqual(result30, "fizzbuzz")
        let result45 = fb.make(with: 45)
        XCTAssertEqual(result45, "fizzbuzz")
    }

    func test_모든3배수일때_fizz출력() {
        for index in stride(from: 3, to: 300, by: 3)
        {
            guard (index % 5 != 0 && index % 15 != 0) else { continue }
            let result = fb.make(with: index)
            XCTAssertEqual(result, "fizz")
        }
    }
    
    func test_모든5배수일때_buzz출력() {
        for index in stride(from: 5, to: 300, by: 5)
        {
            guard (index % 3 != 0 && index % 15 != 0) else { continue }
            let result = fb.make(with: index)
            XCTAssertEqual(result, "buzz")
        }
    }

    func test_모든15배수일때_buzz출력() {
        for index in stride(from: 15, to: 300, by: 15)
        {
            guard (index % 3 != 0 && index % 5 != 0) else { continue }
            let result = fb.make(with: index)
            XCTAssertEqual(result, "fizzbuzz")
        }
    }
    
    func test_모든예외숫자일때_숫자출력() {
        for index in stride(from: 1, to: 300, by: 1)
        {
            guard (index % 3 != 0 && index % 5 != 0 && index % 15 != 0) else { continue }
            let result = fb.make(with: index)
            XCTAssertEqual(result, String(index))
        }
    }

    //MARK:- fizzbuzz array
    
    func test_0일때_빈배열() {
        let result = fb.fizzbuzz(lines: 0)
        XCTAssertEqual(result, [])
    }
    
    func test_1일때_정상배열() {
        let result = fb.fizzbuzz(lines: 1)
        XCTAssertEqual(result, ["1"])
    }
    
    func test_2일때_정상배열() {
        let result = fb.fizzbuzz(lines: 2)
        XCTAssertEqual(result, ["1", "2"])
    }
    
    func test_모든경우_정상배열() {
        let result = fb.fizzbuzz(lines: 300)
        let compare = FizzBuzz()
        var otherResult : [String] = []
        for index in 1...300 {
            otherResult.append(compare.makeIf(with: index))
        }
        XCTAssertEqual(result, otherResult)
    }

}