多国通貨(The Money Example) 歩幅の調整(Times We're Livin' In) 異なる通過間での比較

テスト駆動開発
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原著: Test Driven Development: By Example (Addison-Wesley Signature Series)

開発環境

テスト駆動開発 (Kent Beck(著)、和田卓人(翻訳)、オーム社)の第Ⅰ部(多国通貨(The Money Example))、第9章(歩幅の調整(Times We’re Livin’ In))をJavaではなくGo言語で取り組んでみる。

コード

money_test.go

package money

import "testing"

func TestDollarTimes(t *testing.T) {
	five := NewDollar(5)
	tests := []struct {
		m    int
		want Dollar
	}{
		{2, NewDollar(10)},
		{3, NewDollar(15)},
	}
	for _, test := range tests {
		got := five.Times(test.m)
		want := test.want
		if !got.Eq(want) {
			t.Errorf("%v.Times(%v) got %v, want %v", five, test.m, got, want)
		}
	}
}
func TestDollarEq(t *testing.T) {
	five := NewDollar(5)
	tests := []struct {
		d    Eqer
		want bool
	}{
		{NewDollar(5), true},
		{NewDollar(6), false},
	}
	for _, test := range tests {
		got := five.Eq(test.d)
		if got != test.want {
			t.Errorf("%v.Eq(%v) got %v, want %v",
				five, test.d, got, test.want)
		}
	}
}

func TestFrancTimes(t *testing.T) {
	five := NewFranc(5)
	tests := []struct {
		m    int
		want Franc
	}{
		{2, NewFranc(10)},
		{3, NewFranc(15)},
	}
	for _, test := range tests {
		got := five.Times(test.m)
		want := test.want
		if !got.Eq(want) {
			t.Errorf("%v.Eq(%v) got %v, want %v",
				five, test.m, got, want)
		}
	}
}
func TestFrancEq(t *testing.T) {
	five := NewFranc(5)
	tests := []struct {
		d    Eqer
		want bool
	}{
		{NewFranc(5), true},
		{NewFranc(6), false},
		{NewDollar(5), false},
	}
	for _, test := range tests {
		got := five.Eq(test.d)
		if got != test.want {
			t.Errorf("%v.Eq(%v) got %v, want %v",
				five, test.d, got, test.want)
		}
	}
}

money.go

package money

// Money ...
type Money struct {
	amount   int
	currency string
}

// Currency ...
func (m Money) Currency() string {
	return m.currency
}

// Eqer ...
type Eqer interface {
	Eq(Eqer) bool
}

// Dollar ...
type Dollar struct {
	Money
}

// NewDollar ...
func NewDollar(amount int) Dollar {
	return Dollar{Money{amount: amount, currency: "USD"}}
}

// Times ...
func (d Dollar) Times(m int) Dollar {
	return NewDollar(d.amount * m)
}

// Eq ...
func (d Dollar) Eq(y Eqer) bool {
	dy, ok := y.(Dollar)
	if ok {
		return d.amount == dy.amount
	}
	return false
}

// Franc ...
type Franc struct {
	Money
}

// NewFranc ...
func NewFranc(amount int) Franc {
	return Franc{Money{amount: amount, currency: "CHF"}}
}

// Times ...
func (f Franc) Times(m int) Franc {
	return NewFranc(f.amount * m)
}

// Eq ...
func (f Franc) Eq(y Eqer) bool {
	fy, ok := y.(Franc)
	if ok {
		return f.amount == fy.amount
	}
	return false
}

入出力結果(Terminal, Zsh)

% go test
PASS
ok  	money	0.400s
% go test
PASS
ok  	money	0.278s
%