Go Tutorial Part 9 Deck Project

package main

func main() {
	cards := newDeckFromFile("mydeck")
	cards.shuffle()
	cards.print()
}

package main

import (
	"fmt"
	"io/ioutil"
	"math/rand"
	"os"
	"strings"
	"time"
)

type deck []string

func newDeck() deck {
	cards := deck{}
	cardSuits := []string{"Spades", "Diamonds", "Hearts", "Clubs"}
	cardValues := []string{"Ace", "Two", "Three", "Four"}
	for _, suit := range cardSuits {
		for _, value := range cardValues {
			cards = append(cards, value+" of "+suit)
		}
	}
	return cards
}

func (d deck) print() {
	for i, card := range d {
		fmt.Println(i, card)
	}
}

func deal(d deck, handSize int) (deck, deck) {
	return d[:handSize], d[handSize:]
}

func (d deck) toString() string {
	return strings.Join([]string(d), ",")

}

func (d deck) saveToFile(filename string) error {
	return ioutil.WriteFile(filename, []byte(d.toString()), 0666)
}

func newDeckFromFile(filename string) deck {
	bs, err := ioutil.ReadFile(filename)
	if err != nil {
		fmt.Println("Error:", err)
		os.Exit(1)
	}

	s := strings.Split(string(bs), ",")
	return deck(s)
}

func (d deck) shuffle() {
	source := rand.NewSource(time.Now().UnixNano())
	r := rand.New(source)
	for i := range d {
		newPosition := r.Intn(len(d) - 1)
		d[i], d[newPosition] = d[newPosition], d[i]
	}
}

package main

import (
	"os"
	"testing"
)

func TestNewDeck(t *testing.T) {

	d := newDeck()

	if len(d) != 16 {
		t.Errorf("Expected deck length of 16 but got %v", len(d))
	}

	if d[0] != "Ace of Spades" {
		t.Errorf("Expected first card of Ace o Spades but got %v", d[0])
	}

	if d[len(d)-1] != "Four of Clubs" {
		t.Errorf("Expected last card of Four of Clubs but got %v", d[0])
	}

}

func TestSaveToDeckAndNewDecktFromFile(t *testing.T) {
	os.Remove("_decktesting")
	deck := newDeck()
	deck.saveToFile("_decktesting")
	loadedDeck := newDeckFromFile("_decktesting")

	if len(loadedDeck) != 16 {
		t.Errorf("Expected deck length of 16 but got %v", len(loadedDeck))
	}
	os.Remove("_decktesting")

}