go_slices.go

type itemsList struct {
	items    []int
	mapItems map[int][]int
}

func newItemsList() *itemsList {
	return &itemsList{
		mapItems: make(map[int][]int),
	}
}

func (i *itemsList) SetItems(items []int) {
	i.items = items
}

func (i *itemsList) Items() []int {
	return i.items
}

func (i *itemsList) SetMapItems(idx int, items []int) {
	i.mapItems[idx] = items
}

func (i *itemsList) ItemsAt(idx int) []int {
	return i.mapItems[idx]
}

func TestSliceReturns(t *testing.T) {
	orig := []int{1, 2, 3, 4, 5}
	start := make([]int, len(orig))
	copy(start, orig)

	itemsList := newItemsList()
	itemsList.SetItems(start)

	gotItem := itemsList.Items()
	assert.Equal(t, orig, gotItem)
	// change gotItem
	gotItem[0] = 999

	gotItem2 := itemsList.Items()
	assert.NotEqual(t, orig, gotItem2)
	assert.Equal(t, gotItem, gotItem2)
}

func TestMapSliceReturns(t *testing.T) {
	idx := 1
	orig := []int{1, 2, 3, 4, 5}
	start := make([]int, len(orig))
	copy(start, orig)

	itemsList := newItemsList()
	itemsList.SetMapItems(idx, start)

	gotItem := itemsList.ItemsAt(idx)
	assert.Equal(t, orig, gotItem)
	// change gotItem
	gotItem[0] = 999

	gotItem2 := itemsList.ItemsAt(idx)
	assert.Equal(t, orig, gotItem2)
}