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Source file src/encoding/ascii85/ascii85_test.go

Documentation: encoding/ascii85

     1  // Copyright 2009 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 ascii85
     6  
     7  import (
     8  	"bytes"
     9  	"io"
    10  	"strings"
    11  	"testing"
    12  )
    13  
    14  type testpair struct {
    15  	decoded, encoded string
    16  }
    17  
    18  var bigtest = testpair{
    19  	"Man is distinguished, not only by his reason, but by this singular passion from " +
    20  		"other animals, which is a lust of the mind, that by a perseverance of delight in " +
    21  		"the continued and indefatigable generation of knowledge, exceeds the short " +
    22  		"vehemence of any carnal pleasure.",
    23  	"9jqo^BlbD-BleB1DJ+*+F(f,q/0JhKF<GL>Cj@.4Gp$d7F!,L7@<6@)/0JDEF<G%<+EV:2F!,\n" +
    24  		"O<DJ+*.@<*K0@<6L(Df-\\0Ec5e;DffZ(EZee.Bl.9pF\"AGXBPCsi+DGm>@3BB/F*&OCAfu2/AKY\n" +
    25  		"i(DIb:@FD,*)+C]U=@3BN#EcYf8ATD3s@q?d$AftVqCh[NqF<G:8+EV:.+Cf>-FD5W8ARlolDIa\n" +
    26  		"l(DId<j@<?3r@:F%a+D58'ATD4$Bl@l3De:,-DJs`8ARoFb/0JMK@qB4^F!,R<AKZ&-DfTqBG%G\n" +
    27  		">uD.RTpAKYo'+CT/5+Cei#DII?(E,9)oF*2M7/c\n",
    28  }
    29  
    30  var pairs = []testpair{
    31  	// Encode returns 0 when len(src) is 0
    32  	{
    33  		"",
    34  		"",
    35  	},
    36  	// Wikipedia example
    37  	bigtest,
    38  	// Special case when shortening !!!!! to z.
    39  	{
    40  		"\000\000\000\000",
    41  		"z",
    42  	},
    43  }
    44  
    45  func testEqual(t *testing.T, msg string, args ...any) bool {
    46  	t.Helper()
    47  	if args[len(args)-2] != args[len(args)-1] {
    48  		t.Errorf(msg, args...)
    49  		return false
    50  	}
    51  	return true
    52  }
    53  
    54  func strip85(s string) string {
    55  	t := make([]byte, len(s))
    56  	w := 0
    57  	for r := 0; r < len(s); r++ {
    58  		c := s[r]
    59  		if c > ' ' {
    60  			t[w] = c
    61  			w++
    62  		}
    63  	}
    64  	return string(t[0:w])
    65  }
    66  
    67  func TestEncode(t *testing.T) {
    68  	for _, p := range pairs {
    69  		buf := make([]byte, MaxEncodedLen(len(p.decoded)))
    70  		n := Encode(buf, []byte(p.decoded))
    71  		buf = buf[0:n]
    72  		testEqual(t, "Encode(%q) = %q, want %q", p.decoded, strip85(string(buf)), strip85(p.encoded))
    73  	}
    74  }
    75  
    76  func TestEncoder(t *testing.T) {
    77  	for _, p := range pairs {
    78  		bb := &strings.Builder{}
    79  		encoder := NewEncoder(bb)
    80  		encoder.Write([]byte(p.decoded))
    81  		encoder.Close()
    82  		testEqual(t, "Encode(%q) = %q, want %q", p.decoded, strip85(bb.String()), strip85(p.encoded))
    83  	}
    84  }
    85  
    86  func TestEncoderBuffering(t *testing.T) {
    87  	input := []byte(bigtest.decoded)
    88  	for bs := 1; bs <= 12; bs++ {
    89  		bb := &strings.Builder{}
    90  		encoder := NewEncoder(bb)
    91  		for pos := 0; pos < len(input); pos += bs {
    92  			end := pos + bs
    93  			if end > len(input) {
    94  				end = len(input)
    95  			}
    96  			n, err := encoder.Write(input[pos:end])
    97  			testEqual(t, "Write(%q) gave error %v, want %v", input[pos:end], err, error(nil))
    98  			testEqual(t, "Write(%q) gave length %v, want %v", input[pos:end], n, end-pos)
    99  		}
   100  		err := encoder.Close()
   101  		testEqual(t, "Close gave error %v, want %v", err, error(nil))
   102  		testEqual(t, "Encoding/%d of %q = %q, want %q", bs, bigtest.decoded, strip85(bb.String()), strip85(bigtest.encoded))
   103  	}
   104  }
   105  
   106  func TestDecode(t *testing.T) {
   107  	for _, p := range pairs {
   108  		dbuf := make([]byte, 4*len(p.encoded))
   109  		ndst, nsrc, err := Decode(dbuf, []byte(p.encoded), true)
   110  		testEqual(t, "Decode(%q) = error %v, want %v", p.encoded, err, error(nil))
   111  		testEqual(t, "Decode(%q) = nsrc %v, want %v", p.encoded, nsrc, len(p.encoded))
   112  		testEqual(t, "Decode(%q) = ndst %v, want %v", p.encoded, ndst, len(p.decoded))
   113  		testEqual(t, "Decode(%q) = %q, want %q", p.encoded, string(dbuf[0:ndst]), p.decoded)
   114  	}
   115  }
   116  
   117  func TestDecoder(t *testing.T) {
   118  	for _, p := range pairs {
   119  		decoder := NewDecoder(strings.NewReader(p.encoded))
   120  		dbuf, err := io.ReadAll(decoder)
   121  		if err != nil {
   122  			t.Fatal("Read failed", err)
   123  		}
   124  		testEqual(t, "Read from %q = length %v, want %v", p.encoded, len(dbuf), len(p.decoded))
   125  		testEqual(t, "Decoding of %q = %q, want %q", p.encoded, string(dbuf), p.decoded)
   126  		if err != nil {
   127  			testEqual(t, "Read from %q = %v, want %v", p.encoded, err, io.EOF)
   128  		}
   129  	}
   130  }
   131  
   132  func TestDecoderBuffering(t *testing.T) {
   133  	for bs := 1; bs <= 12; bs++ {
   134  		decoder := NewDecoder(strings.NewReader(bigtest.encoded))
   135  		buf := make([]byte, len(bigtest.decoded)+12)
   136  		var total int
   137  		var n int
   138  		var err error
   139  		for total = 0; total < len(bigtest.decoded) && err == nil; {
   140  			n, err = decoder.Read(buf[total : total+bs])
   141  			total += n
   142  		}
   143  		if err != nil && err != io.EOF {
   144  			t.Errorf("Read from %q at pos %d = %d, unexpected error %v", bigtest.encoded, total, n, err)
   145  		}
   146  		testEqual(t, "Decoding/%d of %q = %q, want %q", bs, bigtest.encoded, string(buf[0:total]), bigtest.decoded)
   147  	}
   148  }
   149  
   150  func TestDecodeCorrupt(t *testing.T) {
   151  	type corrupt struct {
   152  		e string
   153  		p int
   154  	}
   155  	examples := []corrupt{
   156  		{"v", 0},
   157  		{"!z!!!!!!!!!", 1},
   158  	}
   159  
   160  	for _, e := range examples {
   161  		dbuf := make([]byte, 4*len(e.e))
   162  		_, _, err := Decode(dbuf, []byte(e.e), true)
   163  		switch err := err.(type) {
   164  		case CorruptInputError:
   165  			testEqual(t, "Corruption in %q at offset %v, want %v", e.e, int(err), e.p)
   166  		default:
   167  			t.Error("Decoder failed to detect corruption in", e)
   168  		}
   169  	}
   170  }
   171  
   172  func TestBig(t *testing.T) {
   173  	n := 3*1000 + 1
   174  	raw := make([]byte, n)
   175  	const alpha = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
   176  	for i := 0; i < n; i++ {
   177  		raw[i] = alpha[i%len(alpha)]
   178  	}
   179  	encoded := new(bytes.Buffer)
   180  	w := NewEncoder(encoded)
   181  	nn, err := w.Write(raw)
   182  	if nn != n || err != nil {
   183  		t.Fatalf("Encoder.Write(raw) = %d, %v want %d, nil", nn, err, n)
   184  	}
   185  	err = w.Close()
   186  	if err != nil {
   187  		t.Fatalf("Encoder.Close() = %v want nil", err)
   188  	}
   189  	decoded, err := io.ReadAll(NewDecoder(encoded))
   190  	if err != nil {
   191  		t.Fatalf("io.ReadAll(NewDecoder(...)): %v", err)
   192  	}
   193  
   194  	if !bytes.Equal(raw, decoded) {
   195  		var i int
   196  		for i = 0; i < len(decoded) && i < len(raw); i++ {
   197  			if decoded[i] != raw[i] {
   198  				break
   199  			}
   200  		}
   201  		t.Errorf("Decode(Encode(%d-byte string)) failed at offset %d", n, i)
   202  	}
   203  }
   204  
   205  func TestDecoderInternalWhitespace(t *testing.T) {
   206  	s := strings.Repeat(" ", 2048) + "z"
   207  	decoded, err := io.ReadAll(NewDecoder(strings.NewReader(s)))
   208  	if err != nil {
   209  		t.Errorf("Decode gave error %v", err)
   210  	}
   211  	if want := []byte("\000\000\000\000"); !bytes.Equal(want, decoded) {
   212  		t.Errorf("Decode failed: got %v, want %v", decoded, want)
   213  	}
   214  }
   215  

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