// 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 ( "bytes" "io" "io/ioutil" "runtime" "strconv" "strings" "testing" ) type lzwTest struct { desc string raw string compressed string err error } var lzwTests = []lzwTest{ { "empty;LSB;8", "", "\x01\x01", nil, }, { "empty;MSB;8", "", "\x80\x80", nil, }, { "tobe;LSB;7", "TOBEORNOTTOBEORTOBEORNOT", "\x54\x4f\x42\x45\x4f\x52\x4e\x4f\x54\x82\x84\x86\x8b\x85\x87\x89\x81", nil, }, { "tobe;LSB;8", "TOBEORNOTTOBEORTOBEORNOT", "\x54\x9e\x08\x29\xf2\x44\x8a\x93\x27\x54\x04\x12\x34\xb8\xb0\xe0\xc1\x84\x01\x01", nil, }, { "tobe;MSB;7", "TOBEORNOTTOBEORTOBEORNOT", "\x54\x4f\x42\x45\x4f\x52\x4e\x4f\x54\x82\x84\x86\x8b\x85\x87\x89\x81", nil, }, { "tobe;MSB;8", "TOBEORNOTTOBEORTOBEORNOT", "\x2a\x13\xc8\x44\x52\x79\x48\x9c\x4f\x2a\x40\xa0\x90\x68\x5c\x16\x0f\x09\x80\x80", nil, }, { "tobe-truncated;LSB;8", "TOBEORNOTTOBEORTOBEORNOT", "\x54\x9e\x08\x29\xf2\x44\x8a\x93\x27\x54\x04", io.ErrUnexpectedEOF, }, // This example comes from http://en.wikipedia.org/wiki/Graphics_Interchange_Format. { "gif;LSB;8", "\x28\xff\xff\xff\x28\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff", "\x00\x51\xfc\x1b\x28\x70\xa0\xc1\x83\x01\x01", nil, }, // This example comes from http://compgroups.net/comp.lang.ruby/Decompressing-LZW-compression-from-PDF-file { "pdf;MSB;8", "-----A---B", "\x80\x0b\x60\x50\x22\x0c\x0c\x85\x01", nil, }, } func TestReader(t *testing.T) { var b bytes.Buffer for _, tt := range lzwTests { d := strings.Split(tt.desc, ";") var order Order switch d[1] { case "LSB": order = LSB case "MSB": order = MSB default: t.Errorf("%s: bad order %q", tt.desc, d[1]) } litWidth, _ := strconv.Atoi(d[2]) rc := NewReader(strings.NewReader(tt.compressed), order, litWidth) defer rc.Close() b.Reset() n, err := io.Copy(&b, rc) s := b.String() if err != nil { if err != tt.err { t.Errorf("%s: io.Copy: %v want %v", tt.desc, err, tt.err) } if err == io.ErrUnexpectedEOF { // Even if the input is truncated, we should still return the // partial decoded result. if n == 0 || !strings.HasPrefix(tt.raw, s) { t.Errorf("got %d bytes (%q), want a non-empty prefix of %q", n, s, tt.raw) } } continue } if s != tt.raw { t.Errorf("%s: got %d-byte %q want %d-byte %q", tt.desc, n, s, len(tt.raw), tt.raw) } } } func benchmarkDecoder(b *testing.B, n int) { b.StopTimer() b.SetBytes(int64(n)) buf0, err := ioutil.ReadFile("../testdata/e.txt") if err != nil { b.Fatal(err) } if len(buf0) == 0 { b.Fatalf("test file has no data") } compressed := new(bytes.Buffer) w := NewWriter(compressed, LSB, 8) for i := 0; i < n; i += len(buf0) { if len(buf0) > n-i { buf0 = buf0[:n-i] } w.Write(buf0) } w.Close() buf1 := compressed.Bytes() buf0, compressed, w = nil, nil, nil runtime.GC() b.StartTimer() for i := 0; i < b.N; i++ { io.Copy(ioutil.Discard, NewReader(bytes.NewReader(buf1), LSB, 8)) } } func BenchmarkDecoder1e4(b *testing.B) { benchmarkDecoder(b, 1e4) } func BenchmarkDecoder1e5(b *testing.B) { benchmarkDecoder(b, 1e5) } func BenchmarkDecoder1e6(b *testing.B) { benchmarkDecoder(b, 1e6) }