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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package lzw
import (
"io"
"io/ioutil"
"os"
"testing"
)
var filenames = []string{
"../testdata/e.txt",
"../testdata/pi.txt",
}
// testFile tests that compressing and then decompressing the given file with
// the given options yields equivalent bytes to the original file.
func testFile(t *testing.T, fn string, order Order, litWidth int) {
// Read the file, as golden output.
golden, err := os.Open(fn, os.O_RDONLY, 0400)
if err != nil {
t.Errorf("%s (order=%d litWidth=%d): %v", fn, order, litWidth, err)
return
}
defer golden.Close()
// Read the file again, and push it through a pipe that compresses at the write end, and decompresses at the read end.
raw, err := os.Open(fn, os.O_RDONLY, 0400)
if err != nil {
t.Errorf("%s (order=%d litWidth=%d): %v", fn, order, litWidth, err)
return
}
piper, pipew := io.Pipe()
defer piper.Close()
go func() {
defer raw.Close()
defer pipew.Close()
lzww := NewWriter(pipew, order, litWidth)
defer lzww.Close()
var b [4096]byte
for {
n, err0 := raw.Read(b[:])
if err0 != nil && err0 != os.EOF {
t.Errorf("%s (order=%d litWidth=%d): %v", fn, order, litWidth, err0)
return
}
_, err1 := lzww.Write(b[:n])
if err1 == os.EPIPE {
// Fail, but do not report the error, as some other (presumably reportable) error broke the pipe.
return
}
if err1 != nil {
t.Errorf("%s (order=%d litWidth=%d): %v", fn, order, litWidth, err1)
return
}
if err0 == os.EOF {
break
}
}
}()
lzwr := NewReader(piper, order, litWidth)
defer lzwr.Close()
// Compare the two.
b0, err0 := ioutil.ReadAll(golden)
b1, err1 := ioutil.ReadAll(lzwr)
if err0 != nil {
t.Errorf("%s (order=%d litWidth=%d): %v", fn, order, litWidth, err0)
return
}
if err1 != nil {
t.Errorf("%s (order=%d litWidth=%d): %v", fn, order, litWidth, err1)
return
}
if len(b0) != len(b1) {
t.Errorf("%s (order=%d litWidth=%d): length mismatch %d versus %d", fn, order, litWidth, len(b0), len(b1))
return
}
for i := 0; i < len(b0); i++ {
if b0[i] != b1[i] {
t.Errorf("%s (order=%d litWidth=%d): mismatch at %d, 0x%02x versus 0x%02x\n", fn, order, litWidth, i, b0[i], b1[i])
return
}
}
}
func TestWriter(t *testing.T) {
for _, filename := range filenames {
for _, order := range [...]Order{LSB, MSB} {
// The test data "2.71828 etcetera" is ASCII text requiring at least 6 bits.
for _, litWidth := range [...]int{6, 7, 8} {
testFile(t, filename, order, litWidth)
}
}
}
}
func BenchmarkEncoder(b *testing.B) {
b.StopTimer()
buf, _ := ioutil.ReadFile("../testdata/e.txt")
b.StartTimer()
for i := 0; i < b.N; i++ {
w := NewWriter(devNull{}, LSB, 8)
w.Write(buf)
w.Close()
}
}
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