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// Copyright 2009 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 zlib
import (
"bytes"
"fmt"
"internal/testenv"
"io"
"os"
"testing"
)
var filenames = []string{
"../testdata/gettysburg.txt",
"../testdata/e.txt",
"../testdata/pi.txt",
}
var data = []string{
"test a reasonable sized string that can be compressed",
}
// Tests that compressing and then decompressing the given file at the given compression level and dictionary
// yields equivalent bytes to the original file.
func testFileLevelDict(t *testing.T, fn string, level int, d string) {
// Read the file, as golden output.
golden, err := os.Open(fn)
if err != nil {
t.Errorf("%s (level=%d, dict=%q): %v", fn, level, d, err)
return
}
defer golden.Close()
b0, err0 := io.ReadAll(golden)
if err0 != nil {
t.Errorf("%s (level=%d, dict=%q): %v", fn, level, d, err0)
return
}
testLevelDict(t, fn, b0, level, d)
}
func testLevelDict(t *testing.T, fn string, b0 []byte, level int, d string) {
// Make dictionary, if given.
var dict []byte
if d != "" {
dict = []byte(d)
}
// Push data through a pipe that compresses at the write end, and decompresses at the read end.
piper, pipew := io.Pipe()
defer piper.Close()
go func() {
defer pipew.Close()
zlibw, err := NewWriterLevelDict(pipew, level, dict)
if err != nil {
t.Errorf("%s (level=%d, dict=%q): %v", fn, level, d, err)
return
}
defer zlibw.Close()
_, err = zlibw.Write(b0)
if err != nil {
t.Errorf("%s (level=%d, dict=%q): %v", fn, level, d, err)
return
}
}()
zlibr, err := NewReaderDict(piper, dict)
if err != nil {
t.Errorf("%s (level=%d, dict=%q): %v", fn, level, d, err)
return
}
defer zlibr.Close()
// Compare the decompressed data.
b1, err1 := io.ReadAll(zlibr)
if err1 != nil {
t.Errorf("%s (level=%d, dict=%q): %v", fn, level, d, err1)
return
}
if len(b0) != len(b1) {
t.Errorf("%s (level=%d, dict=%q): length mismatch %d versus %d", fn, level, d, len(b0), len(b1))
return
}
for i := 0; i < len(b0); i++ {
if b0[i] != b1[i] {
t.Errorf("%s (level=%d, dict=%q): mismatch at %d, 0x%02x versus 0x%02x\n", fn, level, d, i, b0[i], b1[i])
return
}
}
}
func testFileLevelDictReset(t *testing.T, fn string, level int, dict []byte) {
var b0 []byte
var err error
if fn != "" {
b0, err = os.ReadFile(fn)
if err != nil {
t.Errorf("%s (level=%d): %v", fn, level, err)
return
}
}
// Compress once.
buf := new(bytes.Buffer)
var zlibw *Writer
if dict == nil {
zlibw, err = NewWriterLevel(buf, level)
} else {
zlibw, err = NewWriterLevelDict(buf, level, dict)
}
if err == nil {
_, err = zlibw.Write(b0)
}
if err == nil {
err = zlibw.Close()
}
if err != nil {
t.Errorf("%s (level=%d): %v", fn, level, err)
return
}
out := buf.String()
// Reset and compress again.
buf2 := new(bytes.Buffer)
zlibw.Reset(buf2)
_, err = zlibw.Write(b0)
if err == nil {
err = zlibw.Close()
}
if err != nil {
t.Errorf("%s (level=%d): %v", fn, level, err)
return
}
out2 := buf2.String()
if out2 != out {
t.Errorf("%s (level=%d): different output after reset (got %d bytes, expected %d",
fn, level, len(out2), len(out))
}
}
func TestWriter(t *testing.T) {
for i, s := range data {
b := []byte(s)
tag := fmt.Sprintf("#%d", i)
testLevelDict(t, tag, b, DefaultCompression, "")
testLevelDict(t, tag, b, NoCompression, "")
testLevelDict(t, tag, b, HuffmanOnly, "")
for level := BestSpeed; level <= BestCompression; level++ {
testLevelDict(t, tag, b, level, "")
}
}
}
func TestWriterBig(t *testing.T) {
for i, fn := range filenames {
testFileLevelDict(t, fn, DefaultCompression, "")
testFileLevelDict(t, fn, NoCompression, "")
testFileLevelDict(t, fn, HuffmanOnly, "")
for level := BestSpeed; level <= BestCompression; level++ {
testFileLevelDict(t, fn, level, "")
if level >= 1 && testing.Short() && testenv.Builder() == "" {
break
}
}
if i == 0 && testing.Short() && testenv.Builder() == "" {
break
}
}
}
func TestWriterDict(t *testing.T) {
const dictionary = "0123456789."
for i, fn := range filenames {
testFileLevelDict(t, fn, DefaultCompression, dictionary)
testFileLevelDict(t, fn, NoCompression, dictionary)
testFileLevelDict(t, fn, HuffmanOnly, dictionary)
for level := BestSpeed; level <= BestCompression; level++ {
testFileLevelDict(t, fn, level, dictionary)
if level >= 1 && testing.Short() && testenv.Builder() == "" {
break
}
}
if i == 0 && testing.Short() && testenv.Builder() == "" {
break
}
}
}
func TestWriterReset(t *testing.T) {
const dictionary = "0123456789."
for _, fn := range filenames {
testFileLevelDictReset(t, fn, NoCompression, nil)
testFileLevelDictReset(t, fn, DefaultCompression, nil)
testFileLevelDictReset(t, fn, HuffmanOnly, nil)
testFileLevelDictReset(t, fn, NoCompression, []byte(dictionary))
testFileLevelDictReset(t, fn, DefaultCompression, []byte(dictionary))
testFileLevelDictReset(t, fn, HuffmanOnly, []byte(dictionary))
if testing.Short() {
break
}
for level := BestSpeed; level <= BestCompression; level++ {
testFileLevelDictReset(t, fn, level, nil)
}
}
}
func TestWriterDictIsUsed(t *testing.T) {
var input = []byte("Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.")
var buf bytes.Buffer
compressor, err := NewWriterLevelDict(&buf, BestCompression, input)
if err != nil {
t.Errorf("error in NewWriterLevelDict: %s", err)
return
}
compressor.Write(input)
compressor.Close()
const expectedMaxSize = 25
output := buf.Bytes()
if len(output) > expectedMaxSize {
t.Errorf("result too large (got %d, want <= %d bytes). Is the dictionary being used?", len(output), expectedMaxSize)
}
}
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