Imported Upstream version 1.4upstream/1.4

1 files changed, 152 insertions, 0 deletions

diff --git a/src/compress/lzw/reader_test.go b/src/compress/lzw/reader_test.go
new file mode 100644
index 000000000..9006c91c2
--- /dev/null
+++ b/src/compress/lzw/reader_test.go
@@ -0,0 +1,152 @@
+// 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)
+		if err != nil {
+			if err != tt.err {
+				t.Errorf("%s: io.Copy: %v want %v", tt.desc, err, tt.err)
+			}
+			continue
+		}
+		s := b.String()
+		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)
+}