github.com/razvanm/vanadium-go-1.3@v0.0.0-20160721203343-4a65068e5915/src/compress/lzw/writer_test.go (about) 1 // Copyright 2011 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package lzw 6 7 import ( 8 "io" 9 "io/ioutil" 10 "os" 11 "runtime" 12 "testing" 13 ) 14 15 var filenames = []string{ 16 "../testdata/e.txt", 17 "../testdata/pi.txt", 18 } 19 20 // testFile tests that compressing and then decompressing the given file with 21 // the given options yields equivalent bytes to the original file. 22 func testFile(t *testing.T, fn string, order Order, litWidth int) { 23 // Read the file, as golden output. 24 golden, err := os.Open(fn) 25 if err != nil { 26 t.Errorf("%s (order=%d litWidth=%d): %v", fn, order, litWidth, err) 27 return 28 } 29 defer golden.Close() 30 31 // Read the file again, and push it through a pipe that compresses at the write end, and decompresses at the read end. 32 raw, err := os.Open(fn) 33 if err != nil { 34 t.Errorf("%s (order=%d litWidth=%d): %v", fn, order, litWidth, err) 35 return 36 } 37 38 piper, pipew := io.Pipe() 39 defer piper.Close() 40 go func() { 41 defer raw.Close() 42 defer pipew.Close() 43 lzww := NewWriter(pipew, order, litWidth) 44 defer lzww.Close() 45 var b [4096]byte 46 for { 47 n, err0 := raw.Read(b[:]) 48 if err0 != nil && err0 != io.EOF { 49 t.Errorf("%s (order=%d litWidth=%d): %v", fn, order, litWidth, err0) 50 return 51 } 52 _, err1 := lzww.Write(b[:n]) 53 if err1 != nil { 54 t.Errorf("%s (order=%d litWidth=%d): %v", fn, order, litWidth, err1) 55 return 56 } 57 if err0 == io.EOF { 58 break 59 } 60 } 61 }() 62 lzwr := NewReader(piper, order, litWidth) 63 defer lzwr.Close() 64 65 // Compare the two. 66 b0, err0 := ioutil.ReadAll(golden) 67 b1, err1 := ioutil.ReadAll(lzwr) 68 if err0 != nil { 69 t.Errorf("%s (order=%d litWidth=%d): %v", fn, order, litWidth, err0) 70 return 71 } 72 if err1 != nil { 73 t.Errorf("%s (order=%d litWidth=%d): %v", fn, order, litWidth, err1) 74 return 75 } 76 if len(b1) != len(b0) { 77 t.Errorf("%s (order=%d litWidth=%d): length mismatch %d != %d", fn, order, litWidth, len(b1), len(b0)) 78 return 79 } 80 for i := 0; i < len(b0); i++ { 81 if b1[i] != b0[i] { 82 t.Errorf("%s (order=%d litWidth=%d): mismatch at %d, 0x%02x != 0x%02x\n", fn, order, litWidth, i, b1[i], b0[i]) 83 return 84 } 85 } 86 } 87 88 func TestWriter(t *testing.T) { 89 for _, filename := range filenames { 90 for _, order := range [...]Order{LSB, MSB} { 91 // The test data "2.71828 etcetera" is ASCII text requiring at least 6 bits. 92 for _, litWidth := range [...]int{6, 7, 8} { 93 testFile(t, filename, order, litWidth) 94 } 95 } 96 } 97 } 98 99 func TestWriterReturnValues(t *testing.T) { 100 w := NewWriter(ioutil.Discard, LSB, 8) 101 n, err := w.Write([]byte("asdf")) 102 if n != 4 || err != nil { 103 t.Errorf("got %d, %v, want 4, nil", n, err) 104 } 105 } 106 107 func benchmarkEncoder(b *testing.B, n int) { 108 b.StopTimer() 109 b.SetBytes(int64(n)) 110 buf0, err := ioutil.ReadFile("../testdata/e.txt") 111 if err != nil { 112 b.Fatal(err) 113 } 114 if len(buf0) == 0 { 115 b.Fatalf("test file has no data") 116 } 117 buf1 := make([]byte, n) 118 for i := 0; i < n; i += len(buf0) { 119 if len(buf0) > n-i { 120 buf0 = buf0[:n-i] 121 } 122 copy(buf1[i:], buf0) 123 } 124 buf0 = nil 125 runtime.GC() 126 b.StartTimer() 127 for i := 0; i < b.N; i++ { 128 w := NewWriter(ioutil.Discard, LSB, 8) 129 w.Write(buf1) 130 w.Close() 131 } 132 } 133 134 func BenchmarkEncoder1e4(b *testing.B) { 135 benchmarkEncoder(b, 1e4) 136 } 137 138 func BenchmarkEncoder1e5(b *testing.B) { 139 benchmarkEncoder(b, 1e5) 140 } 141 142 func BenchmarkEncoder1e6(b *testing.B) { 143 benchmarkEncoder(b, 1e6) 144 }