gen_testdata.go

// +build ignore

// gen_testdata clones the utf-8 tests data to the other
// unicode encodings and adds BOM variants of each.
package main

import (
	"io/ioutil"
	"log"
	"os"
	"path/filepath"

	"golang.org/x/text/encoding"
	"golang.org/x/text/encoding/unicode"
)

func main() {
	var xforms = []struct {
		dir, bom string
		enc      encoding.Encoding
	}{
		{"testdata/utf-16be", "\xFE\xFF", unicode.UTF16(unicode.BigEndian, unicode.IgnoreBOM)},
		{"testdata/utf-16le", "\xFF\xFE", unicode.UTF16(unicode.LittleEndian, unicode.IgnoreBOM)},
	}

	paths, _ := filepath.Glob("testdata/utf-8/*")
	for _, p := range paths {
		src, err := ioutil.ReadFile(p)
		if err != nil {
			log.Fatal(err)
		}

		write("testdata/utf-8_bom", p, "\xEF\xBB\xBF", src)
		for _, xform := range xforms {
			dst, err := xform.enc.NewEncoder().Bytes(src)
			if err != nil {
				log.Fatal(err)
			}
			write(xform.dir, p, "", dst)
			write(xform.dir+"_bom", p, xform.bom, dst)
		}
	}
}

func write(dir, orig, bom string, buf []byte) {
	f, err := os.Create(filepath.Join(dir, filepath.Base(orig)))
	if err != nil {
		log.Fatal(err)
	}
	if _, err = f.Write([]byte(bom)); err != nil {
		log.Fatal(err)
	}
	if _, err = f.Write(buf); err != nil {
		log.Fatal(err)
	}
}