GoConvey Sample

sample.go

package sample

import "errors"

func HexStringToInteger(s string) (int, error) {
	num := 0
	signum := 1

	if signum == 0 {
		return 0, nil
	}

	for i, j := range(s) {
		switch {
		case j == '-' && i == 0: signum = -1
		case '0' <= j && j <= '9': num = num * 16 + int(j - '0')
		case 'a' <= j && j <= 'f': num = num * 16 + int(j - 'a') + 10
		case 'A' <= j && j <= 'F': num = num * 16 + int(j - 'A') + 10
		default: return 0, errors.New("Unexpected char")
		}
	}

	return num * signum, nil
}

sample_test.go

package sample

import (
	"errors"
	"testing"
	. "github.com/smartystreets/goconvey/convey"
)

func TestHexStringToInteger(t *testing.T) {

	Convey("数字とa〜fだけの文字列のときは数値を返す", t, func() {
		r, _ := HexStringToInteger("0")
		So(r, ShouldEqual, 0)

		r, _ = HexStringToInteger("1")
		So(r, ShouldEqual, 1)

		r, _ = HexStringToInteger("c")
		So(r, ShouldEqual, 12)

		r, _ = HexStringToInteger("10")
		So(r, ShouldEqual, 16)

		r, _ = HexStringToInteger("64")
		So(r, ShouldEqual, 100)

		r, _ = HexStringToInteger("ff")
		So(r, ShouldEqual, 255)
	})

	Convey("数字とA〜Fだけの文字列をときは数値を返す", t, func() {
		r, _ := HexStringToInteger("FF")
		So(r, ShouldEqual, 255)

		r, _ = HexStringToInteger("FFFF")
		So(r, ShouldEqual, 65535)
	})

	Convey("先頭の-が付いているときは負の値を返す", t, func() {
		r, _ := HexStringToInteger("-FF")
		So(r, ShouldEqual, -255)
	})

	Convey("先頭以外に-を含むときはエラーを返す", t, func() {
		r, e := HexStringToInteger("F-F")
		So(r, ShouldEqual, 0)
		So(e, ShouldHaveSameTypeAs, errors.New(""))

		r, e = HexStringToInteger("FF-")
		So(r, ShouldEqual, 0)
		So(e, ShouldHaveSameTypeAs, errors.New(""))
	})

	Convey("数値とA〜F、a〜f以外の文字を含む場合はエラーを返す", t, func() {
		r, e := HexStringToInteger("q")
		So(r, ShouldEqual, 0)
		So(e, ShouldHaveSameTypeAs, errors.New(""))
	})

}