libgo/go/bufio/scan_test.go

   1 // Copyright 2013 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 bufio_test
   6
   7 import (
   8         . "bufio"
   9         "bytes"
  10         "errors"
  11         "io"
  12         "strings"
  13         "testing"
  14         "unicode"
  15         "unicode/utf8"
  16 )
  17
  18 const smallMaxTokenSize = 256 // Much smaller for more efficient testing.
  19
  20 // Test white space table matches the Unicode definition.
  21 func TestSpace(t *testing.T) {
  22         for r := rune(0); r <= utf8.MaxRune; r++ {
  23                 if IsSpace(r) != unicode.IsSpace(r) {
  24                         t.Fatalf("white space property disagrees: %#U should be %t", r, unicode.IsSpace(r))
  25                 }
  26         }
  27 }
  28
  29 var scanTests = []string{
  30         "",
  31         "a",
  32         "¼",
  33         "☹",
  34         "\x81",   // UTF-8 error
  35         "\uFFFD", // correctly encoded RuneError
  36         "abcdefgh",
  37         "abc def\n\t\tgh    ",
  38         "abc¼☹\x81\uFFFD日本語\x82abc",
  39 }
  40
  41 func TestScanByte(t *testing.T) {
  42         for n, test := range scanTests {
  43                 buf := strings.NewReader(test)
  44                 s := NewScanner(buf)
  45                 s.Split(ScanBytes)
  46                 var i int
  47                 for i = 0; s.Scan(); i++ {
  48                         if b := s.Bytes(); len(b) != 1 || b[0] != test[i] {
  49                                 t.Errorf("#%d: %d: expected %q got %q", n, i, test, b)
  50                         }
  51                 }
  52                 if i != len(test) {
  53                         t.Errorf("#%d: termination expected at %d; got %d", n, len(test), i)
  54                 }
  55                 err := s.Err()
  56                 if err != nil {
  57                         t.Errorf("#%d: %v", n, err)
  58                 }
  59         }
  60 }
  61
  62 // Test that the rune splitter returns same sequence of runes (not bytes) as for range string.
  63 func TestScanRune(t *testing.T) {
  64         for n, test := range scanTests {
  65                 buf := strings.NewReader(test)
  66                 s := NewScanner(buf)
  67                 s.Split(ScanRunes)
  68                 var i, runeCount int
  69                 var expect rune
  70                 // Use a string range loop to validate the sequence of runes.
  71                 for i, expect = range string(test) {
  72                         if !s.Scan() {
  73                                 break
  74                         }
  75                         runeCount++
  76                         got, _ := utf8.DecodeRune(s.Bytes())
  77                         if got != expect {
  78                                 t.Errorf("#%d: %d: expected %q got %q", n, i, expect, got)
  79                         }
  80                 }
  81                 if s.Scan() {
  82                         t.Errorf("#%d: scan ran too long, got %q", n, s.Text())
  83                 }
  84                 testRuneCount := utf8.RuneCountInString(test)
  85                 if runeCount != testRuneCount {
  86                         t.Errorf("#%d: termination expected at %d; got %d", n, testRuneCount, runeCount)
  87                 }
  88                 err := s.Err()
  89                 if err != nil {
  90                         t.Errorf("#%d: %v", n, err)
  91                 }
  92         }
  93 }
  94
  95 var wordScanTests = []string{
  96         "",
  97         " ",
  98         "\n",
  99         "a",
 100         " a ",
 101         "abc def",
 102         " abc def ",
 103         " abc\tdef\nghi\rjkl\fmno\vpqr\u0085stu\u00a0\n",
 104 }
 105
 106 // Test that the word splitter returns the same data as strings.Fields.
 107 func TestScanWords(t *testing.T) {
 108         for n, test := range wordScanTests {
 109                 buf := strings.NewReader(test)
 110                 s := NewScanner(buf)
 111                 s.Split(ScanWords)
 112                 words := strings.Fields(test)
 113                 var wordCount int
 114                 for wordCount = 0; wordCount < len(words); wordCount++ {
 115                         if !s.Scan() {
 116                                 break
 117                         }
 118                         got := s.Text()
 119                         if got != words[wordCount] {
 120                                 t.Errorf("#%d: %d: expected %q got %q", n, wordCount, words[wordCount], got)
 121                         }
 122                 }
 123                 if s.Scan() {
 124                         t.Errorf("#%d: scan ran too long, got %q", n, s.Text())
 125                 }
 126                 if wordCount != len(words) {
 127                         t.Errorf("#%d: termination expected at %d; got %d", n, len(words), wordCount)
 128                 }
 129                 err := s.Err()
 130                 if err != nil {
 131                         t.Errorf("#%d: %v", n, err)
 132                 }
 133         }
 134 }
 135
 136 // slowReader is a reader that returns only a few bytes at a time, to test the incremental
 137 // reads in Scanner.Scan.
 138 type slowReader struct {
 139         max int
 140         buf io.Reader
 141 }
 142
 143 func (sr *slowReader) Read(p []byte) (n int, err error) {
 144         if len(p) > sr.max {
 145                 p = p[0:sr.max]
 146         }
 147         return sr.buf.Read(p)
 148 }
 149
 150 // genLine writes to buf a predictable but non-trivial line of text of length
 151 // n, including the terminal newline and an occasional carriage return.
 152 // If addNewline is false, the \r and \n are not emitted.
 153 func genLine(buf *bytes.Buffer, lineNum, n int, addNewline bool) {
 154         buf.Reset()
 155         doCR := lineNum%5 == 0
 156         if doCR {
 157                 n--
 158         }
 159         for i := 0; i < n-1; i++ { // Stop early for \n.
 160                 c := 'a' + byte(lineNum+i)
 161                 if c == '\n' || c == '\r' { // Don't confuse us.
 162                         c = 'N'
 163                 }
 164                 buf.WriteByte(c)
 165         }
 166         if addNewline {
 167                 if doCR {
 168                         buf.WriteByte('\r')
 169                 }
 170                 buf.WriteByte('\n')
 171         }
 172 }
 173
 174 // Test the line splitter, including some carriage returns but no long lines.
 175 func TestScanLongLines(t *testing.T) {
 176         // Build a buffer of lots of line lengths up to but not exceeding smallMaxTokenSize.
 177         tmp := new(bytes.Buffer)
 178         buf := new(bytes.Buffer)
 179         lineNum := 0
 180         j := 0
 181         for i := 0; i < 2*smallMaxTokenSize; i++ {
 182                 genLine(tmp, lineNum, j, true)
 183                 if j < smallMaxTokenSize {
 184                         j++
 185                 } else {
 186                         j--
 187                 }
 188                 buf.Write(tmp.Bytes())
 189                 lineNum++
 190         }
 191         s := NewScanner(&slowReader{1, buf})
 192         s.Split(ScanLines)
 193         s.MaxTokenSize(smallMaxTokenSize)
 194         j = 0
 195         for lineNum := 0; s.Scan(); lineNum++ {
 196                 genLine(tmp, lineNum, j, false)
 197                 if j < smallMaxTokenSize {
 198                         j++
 199                 } else {
 200                         j--
 201                 }
 202                 line := tmp.String() // We use the string-valued token here, for variety.
 203                 if s.Text() != line {
 204                         t.Errorf("%d: bad line: %d %d\n%.100q\n%.100q\n", lineNum, len(s.Bytes()), len(line), s.Text(), line)
 205                 }
 206         }
 207         err := s.Err()
 208         if err != nil {
 209                 t.Fatal(err)
 210         }
 211 }
 212
 213 // Test that the line splitter errors out on a long line.
 214 func TestScanLineTooLong(t *testing.T) {
 215         const smallMaxTokenSize = 256 // Much smaller for more efficient testing.
 216         // Build a buffer of lots of line lengths up to but not exceeding smallMaxTokenSize.
 217         tmp := new(bytes.Buffer)
 218         buf := new(bytes.Buffer)
 219         lineNum := 0
 220         j := 0
 221         for i := 0; i < 2*smallMaxTokenSize; i++ {
 222                 genLine(tmp, lineNum, j, true)
 223                 j++
 224                 buf.Write(tmp.Bytes())
 225                 lineNum++
 226         }
 227         s := NewScanner(&slowReader{3, buf})
 228         s.Split(ScanLines)
 229         s.MaxTokenSize(smallMaxTokenSize)
 230         j = 0
 231         for lineNum := 0; s.Scan(); lineNum++ {
 232                 genLine(tmp, lineNum, j, false)
 233                 if j < smallMaxTokenSize {
 234                         j++
 235                 } else {
 236                         j--
 237                 }
 238                 line := tmp.Bytes()
 239                 if !bytes.Equal(s.Bytes(), line) {
 240                         t.Errorf("%d: bad line: %d %d\n%.100q\n%.100q\n", lineNum, len(s.Bytes()), len(line), s.Bytes(), line)
 241                 }
 242         }
 243         err := s.Err()
 244         if err != ErrTooLong {
 245                 t.Fatalf("expected ErrTooLong; got %s", err)
 246         }
 247 }
 248
 249 // Test that the line splitter handles a final line without a newline.
 250 func testNoNewline(text string, lines []string, t *testing.T) {
 251         buf := strings.NewReader(text)
 252         s := NewScanner(&slowReader{7, buf})
 253         s.Split(ScanLines)
 254         for lineNum := 0; s.Scan(); lineNum++ {
 255                 line := lines[lineNum]
 256                 if s.Text() != line {
 257                         t.Errorf("%d: bad line: %d %d\n%.100q\n%.100q\n", lineNum, len(s.Bytes()), len(line), s.Bytes(), line)
 258                 }
 259         }
 260         err := s.Err()
 261         if err != nil {
 262                 t.Fatal(err)
 263         }
 264 }
 265
 266 // Test that the line splitter handles a final line without a newline.
 267 func TestScanLineNoNewline(t *testing.T) {
 268         const text = "abcdefghijklmn\nopqrstuvwxyz"
 269         lines := []string{
 270                 "abcdefghijklmn",
 271                 "opqrstuvwxyz",
 272         }
 273         testNoNewline(text, lines, t)
 274 }
 275
 276 // Test that the line splitter handles a final line with a carriage return but no newline.
 277 func TestScanLineReturnButNoNewline(t *testing.T) {
 278         const text = "abcdefghijklmn\nopqrstuvwxyz\r"
 279         lines := []string{
 280                 "abcdefghijklmn",
 281                 "opqrstuvwxyz",
 282         }
 283         testNoNewline(text, lines, t)
 284 }
 285
 286 // Test that the line splitter handles a final empty line.
 287 func TestScanLineEmptyFinalLine(t *testing.T) {
 288         const text = "abcdefghijklmn\nopqrstuvwxyz\n\n"
 289         lines := []string{
 290                 "abcdefghijklmn",
 291                 "opqrstuvwxyz",
 292                 "",
 293         }
 294         testNoNewline(text, lines, t)
 295 }
 296
 297 // Test that the line splitter handles a final empty line with a carriage return but no newline.
 298 func TestScanLineEmptyFinalLineWithCR(t *testing.T) {
 299         const text = "abcdefghijklmn\nopqrstuvwxyz\n\r"
 300         lines := []string{
 301                 "abcdefghijklmn",
 302                 "opqrstuvwxyz",
 303                 "",
 304         }
 305         testNoNewline(text, lines, t)
 306 }
 307
 308 var testError = errors.New("testError")
 309
 310 // Test the correct error is returned when the split function errors out.
 311 func TestSplitError(t *testing.T) {
 312         // Create a split function that delivers a little data, then a predictable error.
 313         numSplits := 0
 314         const okCount = 7
 315         errorSplit := func(data []byte, atEOF bool) (advance int, token []byte, err error) {
 316                 if atEOF {
 317                         panic("didn't get enough data")
 318                 }
 319                 if numSplits >= okCount {
 320                         return 0, nil, testError
 321                 }
 322                 numSplits++
 323                 return 1, data[0:1], nil
 324         }
 325         // Read the data.
 326         const text = "abcdefghijklmnopqrstuvwxyz"
 327         buf := strings.NewReader(text)
 328         s := NewScanner(&slowReader{1, buf})
 329         s.Split(errorSplit)
 330         var i int
 331         for i = 0; s.Scan(); i++ {
 332                 if len(s.Bytes()) != 1 || text[i] != s.Bytes()[0] {
 333                         t.Errorf("#%d: expected %q got %q", i, text[i], s.Bytes()[0])
 334                 }
 335         }
 336         // Check correct termination location and error.
 337         if i != okCount {
 338                 t.Errorf("unexpected termination; expected %d tokens got %d", okCount, i)
 339         }
 340         err := s.Err()
 341         if err != testError {
 342                 t.Fatalf("expected %q got %v", testError, err)
 343         }
 344 }
 345
 346 // Test that an EOF is overridden by a user-generated scan error.
 347 func TestErrAtEOF(t *testing.T) {
 348         s := NewScanner(strings.NewReader("1 2 33"))
 349         // This splitter will fail on last entry, after s.err==EOF.
 350         split := func(data []byte, atEOF bool) (advance int, token []byte, err error) {
 351                 advance, token, err = ScanWords(data, atEOF)
 352                 if len(token) > 1 {
 353                         if s.ErrOrEOF() != io.EOF {
 354                                 t.Fatal("not testing EOF")
 355                         }
 356                         err = testError
 357                 }
 358                 return
 359         }
 360         s.Split(split)
 361         for s.Scan() {
 362         }
 363         if s.Err() != testError {
 364                 t.Fatal("wrong error:", s.Err())
 365         }
 366 }
 367
 368 // Test for issue 5268.
 369 type alwaysError struct{}
 370
 371 func (alwaysError) Read(p []byte) (int, error) {
 372         return 0, io.ErrUnexpectedEOF
 373 }
 374
 375 func TestNonEOFWithEmptyRead(t *testing.T) {
 376         scanner := NewScanner(alwaysError{})
 377         for scanner.Scan() {
 378                 t.Fatal("read should fail")
 379         }
 380         err := scanner.Err()
 381         if err != io.ErrUnexpectedEOF {
 382                 t.Errorf("unexpected error: %v", err)
 383         }
 384 }
 385
 386 // Test that Scan finishes if we have endless empty reads.
 387 type endlessZeros struct{}
 388
 389 func (endlessZeros) Read(p []byte) (int, error) {
 390         return 0, nil
 391 }
 392
 393 func TestBadReader(t *testing.T) {
 394         scanner := NewScanner(endlessZeros{})
 395         for scanner.Scan() {
 396                 t.Fatal("read should fail")
 397         }
 398         err := scanner.Err()
 399         if err != io.ErrNoProgress {
 400                 t.Errorf("unexpected error: %v", err)
 401         }
 402 }
 403
 404 func TestScanWordsExcessiveWhiteSpace(t *testing.T) {
 405         const word = "ipsum"
 406         s := strings.Repeat(" ", 4*smallMaxTokenSize) + word
 407         scanner := NewScanner(strings.NewReader(s))
 408         scanner.MaxTokenSize(smallMaxTokenSize)
 409         scanner.Split(ScanWords)
 410         if !scanner.Scan() {
 411                 t.Fatalf("scan failed: %v", scanner.Err())
 412         }
 413         if token := scanner.Text(); token != word {
 414                 t.Fatalf("unexpected token: %v", token)
 415         }
 416 }
 417
 418 // Test that empty tokens, including at end of line or end of file, are found by the scanner.
 419 // Issue 8672: Could miss final empty token.
 420
 421 func commaSplit(data []byte, atEOF bool) (advance int, token []byte, err error) {
 422         for i := 0; i < len(data); i++ {
 423                 if data[i] == ',' {
 424                         return i + 1, data[:i], nil
 425                 }
 426         }
 427         return 0, data, ErrFinalToken
 428 }
 429
 430 func testEmptyTokens(t *testing.T, text string, values []string) {
 431         s := NewScanner(strings.NewReader(text))
 432         s.Split(commaSplit)
 433         var i int
 434         for i = 0; s.Scan(); i++ {
 435                 if i >= len(values) {
 436                         t.Fatalf("got %d fields, expected %d", i+1, len(values))
 437                 }
 438                 if s.Text() != values[i] {
 439                         t.Errorf("%d: expected %q got %q", i, values[i], s.Text())
 440                 }
 441         }
 442         if i != len(values) {
 443                 t.Fatalf("got %d fields, expected %d", i, len(values))
 444         }
 445         if err := s.Err(); err != nil {
 446                 t.Fatal(err)
 447         }
 448 }
 449
 450 func TestEmptyTokens(t *testing.T) {
 451         testEmptyTokens(t, "1,2,3,", []string{"1", "2", "3", ""})
 452 }
 453
 454 func TestWithNoEmptyTokens(t *testing.T) {
 455         testEmptyTokens(t, "1,2,3", []string{"1", "2", "3"})
 456 }
 457
 458 func loopAtEOFSplit(data []byte, atEOF bool) (advance int, token []byte, err error) {
 459         if len(data) > 0 {
 460                 return 1, data[:1], nil
 461         }
 462         return 0, data, nil
 463 }
 464
 465 func TestDontLoopForever(t *testing.T) {
 466         s := NewScanner(strings.NewReader("abc"))
 467         s.Split(loopAtEOFSplit)
 468         // Expect a panic
 469         defer func() {
 470                 err := recover()
 471                 if err == nil {
 472                         t.Fatal("should have panicked")
 473                 }
 474                 if msg, ok := err.(string); !ok || !strings.Contains(msg, "empty tokens") {
 475                         panic(err)
 476                 }
 477         }()
 478         for count := 0; s.Scan(); count++ {
 479                 if count > 1000 {
 480                         t.Fatal("looping")
 481                 }
 482         }
 483         if s.Err() != nil {
 484                 t.Fatal("after scan:", s.Err())
 485         }
 486 }
 487
 488 func TestBlankLines(t *testing.T) {
 489         s := NewScanner(strings.NewReader(strings.Repeat("\n", 1000)))
 490         for count := 0; s.Scan(); count++ {
 491                 if count > 2000 {
 492                         t.Fatal("looping")
 493                 }
 494         }
 495         if s.Err() != nil {
 496                 t.Fatal("after scan:", s.Err())
 497         }
 498 }
 499
 500 type countdown int
 501
 502 func (c *countdown) split(data []byte, atEOF bool) (advance int, token []byte, err error) {
 503         if *c > 0 {
 504                 *c--
 505                 return 1, data[:1], nil
 506         }
 507         return 0, nil, nil
 508 }
 509
 510 // Check that the looping-at-EOF check doesn't trigger for merely empty tokens.
 511 func TestEmptyLinesOK(t *testing.T) {
 512         c := countdown(10000)
 513         s := NewScanner(strings.NewReader(strings.Repeat("\n", 10000)))
 514         s.Split(c.split)
 515         for s.Scan() {
 516         }
 517         if s.Err() != nil {
 518                 t.Fatal("after scan:", s.Err())
 519         }
 520         if c != 0 {
 521                 t.Fatalf("stopped with %d left to process", c)
 522         }
 523 }
 524
 525 // Make sure we can read a huge token if a big enough buffer is provided.
 526 func TestHugeBuffer(t *testing.T) {
 527         text := strings.Repeat("x", 2*MaxScanTokenSize)
 528         s := NewScanner(strings.NewReader(text + "\n"))
 529         s.Buffer(make([]byte, 100), 3*MaxScanTokenSize)
 530         for s.Scan() {
 531                 token := s.Text()
 532                 if token != text {
 533                         t.Errorf("scan got incorrect token of length %d", len(token))
 534                 }
 535         }
 536         if s.Err() != nil {
 537                 t.Fatal("after scan:", s.Err())
 538         }
 539 }