ペアプロTDDを楽しむ会 in DarkでやったFizzBuzzのお題。

FizzBuzzTDD.swift

// FizzBuzzTests.swift

import XCTest
@testable import FizzBuzz

class FizzBuzzTests: XCTestCase {
    func test数字を渡すとnumberを返す() {
        XCTContext.runActivity(named: "2を渡した場合") { _ in
            let fizzBuzz = FizzBuzz(2)
            XCTContext.runActivity(named: "number(2)を返す") { _ in
                XCTAssertEqual(.number(2), fizzBuzz.judge())
            }
        }
        
        XCTContext.runActivity(named: "1を渡した場合") { _ in
            let fizzBuzz = FizzBuzz(1)
            XCTContext.runActivity(named: "number(1)を返す") { _ in
                XCTAssertEqual(.number(1), fizzBuzz.judge())
            }
        }
    }
    
    func test3の倍数を渡すとfizzを返す() {
        XCTContext.runActivity(named: "3を渡した場合") { _ in
            let fizzBuzz = FizzBuzz(3)
            XCTContext.runActivity(named: "fizzを返す") { _ in
                XCTAssertEqual(.fizz, fizzBuzz.judge())
            }
        }

        XCTContext.runActivity(named: "6を渡した場合") { _ in
            let fizzBuzz = FizzBuzz(6)
            XCTContext.runActivity(named: "fizzを返す") { _ in
                XCTAssertEqual(.fizz, fizzBuzz.judge())
            }
        }
    }
    
    func test5の倍数を渡すとbuzzを返す() {
        XCTContext.runActivity(named: "5を渡した場合") { _ in
            let fizzBuzz = FizzBuzz(5)
            XCTContext.runActivity(named: "buzzを返す") { _ in
                XCTAssertEqual(.buzz, fizzBuzz.judge())
            }
        }
        
        XCTContext.runActivity(named: "10を渡した場合") { _ in
            let fizzBuzz = FizzBuzz(10)
            XCTContext.runActivity(named: "buzzを返す") { _ in
                XCTAssertEqual(.buzz, fizzBuzz.judge())
            }
        }
    }
    
    func test3と5の公倍数を渡すとfizzBuzzを返す() {
        XCTContext.runActivity(named: "15を渡した場合") { _ in
            let fizzBuzz = FizzBuzz(15)
            XCTContext.runActivity(named: "fizzBuzzを返す") { _ in
                XCTAssertEqual(.fizzBuzz, fizzBuzz.judge())
            }
        }
        
        XCTContext.runActivity(named: "30を渡した場合") { _ in
            let fizzBuzz = FizzBuzz(30)
            XCTContext.runActivity(named: "fizzBuzzを返す") { _ in
                XCTAssertEqual(.fizzBuzz, fizzBuzz.judge())
            }
        }
    }
}

// -------------------------------

// FizzBuzz.swift
import Foundation

enum FizzBuzzResult: Equatable {
    case number(Int)
    case fizz
    case buzz
    case fizzBuzz
    
    static func ==(lhs: FizzBuzzResult, rhs: FizzBuzzResult) -> Bool {
        switch (lhs, rhs) {
        case (.fizz, .fizz), (.buzz, .buzz), (.fizzBuzz, .fizzBuzz):
            return true
            
        case (.number(let lhsValue), .number(let rhsValue)) where lhsValue == rhsValue:
            return true
            
        default:
            return false
        }
    }
}

struct FizzBuzz {
    private var number: Int
    
    init(_ number: Int) {
        self.number = number
    }
    
    func judge() -> FizzBuzzResult {
        if number % 3 == 0 && number % 5 == 0 {
            return .fizzBuzz
        }
        
        if number % 3 == 0 {
            return .fizz
        }
        
        if number % 5 == 0 {
            return .buzz
        }
        
        return .number(number)
    }
}