You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: encoder_test.go
    path of file: ./repos/barcode/aztec
    
    the code of the file until where you have to start completion: package aztec

import (
	"strings"
	"testing"

	"github.com/boombuler/barcode/utils"
)

func Test_StuffBits(t *testing.T) {
	testStuffBits := func(wordSize int
    
func Test_StuffBits(t *testing.T) {
	testStuffBits := func(wordSize int, bits string, expected string) {
		bl := new(utils.BitList)
		for _, r := range bits {
			if r == 'X' {
				bl.AddBit(true)
			} else if r == '.' {
				bl.AddBit(false)
			}
		}
		stuffed := stuffBits(bl, wordSize)
		expectedBits := strings.Replace(expected, " ", "", -1)
		result := bitStr(stuffed)

		if result != expectedBits {
			t.Errorf("stuffBits failed for %q\nGot: %q", bits, result)
		}
	}

	testStuffBits(5, ".X.X. X.X.X .X.X.",
		".X.X. X.X.X .X.X.")
	testStuffBits(5, ".X.X. ..... .X.X",
		".X.X. ....X ..X.X")
	testStuffBits(3, "XX. ... ... ..X XXX .X. ..",
		"XX. ..X ..X ..X ..X .XX XX. .X. ..X")
	testStuffBits(6, ".X.X.. ...... ..X.XX",
		".X.X.. .....X. ..X.XX XXXX.")
	testStuffBits(6, ".X.X.. ...... ...... ..X.X.",
		".X.X.. .....X .....X ....X. X.XXXX")
	testStuffBits(6, ".X.X.. XXXXXX ...... ..X.XX",
		".X.X.. XXXXX. X..... ...X.X XXXXX.")
	testStuffBits(6,
		"...... ..XXXX X..XX. .X.... .X.X.X .....X .X.... ...X.X .....X ....XX ..X... ....X. X..XXX X.XX.X",
		".....X ...XXX XX..XX ..X... ..X.X. X..... X.X... ....X. X..... X....X X..X.. .....X X.X..X XXX.XX .XXXXX")
}