242 lines
6.5 KiB
Go
242 lines
6.5 KiB
Go
// Copyright (c) 2014 Couchbase, Inc.
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
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// except in compliance with the License. You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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// Unless required by applicable law or agreed to in writing, software distributed under the
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// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
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// either express or implied. See the License for the specific language governing permissions
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// and limitations under the License.
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package segment
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import (
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"bufio"
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"bytes"
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"errors"
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"io"
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"strings"
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"testing"
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)
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// Tests borrowed from Scanner to test Segmenter
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// slowReader is a reader that returns only a few bytes at a time, to test the incremental
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// reads in Scanner.Scan.
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type slowReader struct {
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max int
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buf io.Reader
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}
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func (sr *slowReader) Read(p []byte) (n int, err error) {
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if len(p) > sr.max {
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p = p[0:sr.max]
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}
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return sr.buf.Read(p)
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}
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// genLine writes to buf a predictable but non-trivial line of text of length
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// n, including the terminal newline and an occasional carriage return.
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// If addNewline is false, the \r and \n are not emitted.
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func genLine(buf *bytes.Buffer, lineNum, n int, addNewline bool) {
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buf.Reset()
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doCR := lineNum%5 == 0
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if doCR {
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n--
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}
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for i := 0; i < n-1; i++ { // Stop early for \n.
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c := 'a' + byte(lineNum+i)
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if c == '\n' || c == '\r' { // Don't confuse us.
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c = 'N'
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}
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buf.WriteByte(c)
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}
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if addNewline {
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if doCR {
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buf.WriteByte('\r')
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}
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buf.WriteByte('\n')
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}
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return
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}
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func wrapSplitFuncAsSegmentFuncForTesting(splitFunc bufio.SplitFunc) SegmentFunc {
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return func(data []byte, atEOF bool) (advance int, token []byte, typ int, err error) {
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typ = 0
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advance, token, err = splitFunc(data, atEOF)
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return
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}
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}
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// Test that the line segmenter errors out on a long line.
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func TestSegmentTooLong(t *testing.T) {
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const smallMaxTokenSize = 256 // Much smaller for more efficient testing.
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// Build a buffer of lots of line lengths up to but not exceeding smallMaxTokenSize.
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tmp := new(bytes.Buffer)
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buf := new(bytes.Buffer)
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lineNum := 0
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j := 0
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for i := 0; i < 2*smallMaxTokenSize; i++ {
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genLine(tmp, lineNum, j, true)
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j++
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buf.Write(tmp.Bytes())
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lineNum++
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}
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s := NewSegmenter(&slowReader{3, buf})
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// change to line segmenter for testing
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s.SetSegmenter(wrapSplitFuncAsSegmentFuncForTesting(bufio.ScanLines))
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s.MaxTokenSize(smallMaxTokenSize)
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j = 0
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for lineNum := 0; s.Segment(); lineNum++ {
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genLine(tmp, lineNum, j, false)
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if j < smallMaxTokenSize {
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j++
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} else {
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j--
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}
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line := tmp.Bytes()
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if !bytes.Equal(s.Bytes(), line) {
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t.Errorf("%d: bad line: %d %d\n%.100q\n%.100q\n", lineNum, len(s.Bytes()), len(line), s.Bytes(), line)
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}
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}
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err := s.Err()
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if err != ErrTooLong {
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t.Fatalf("expected ErrTooLong; got %s", err)
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}
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}
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var testError = errors.New("testError")
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// Test the correct error is returned when the split function errors out.
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func TestSegmentError(t *testing.T) {
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// Create a split function that delivers a little data, then a predictable error.
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numSplits := 0
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const okCount = 7
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errorSplit := func(data []byte, atEOF bool) (advance int, token []byte, err error) {
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if atEOF {
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panic("didn't get enough data")
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}
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if numSplits >= okCount {
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return 0, nil, testError
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}
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numSplits++
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return 1, data[0:1], nil
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}
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// Read the data.
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const text = "abcdefghijklmnopqrstuvwxyz"
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buf := strings.NewReader(text)
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s := NewSegmenter(&slowReader{1, buf})
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// change to line segmenter for testing
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s.SetSegmenter(wrapSplitFuncAsSegmentFuncForTesting(errorSplit))
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var i int
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for i = 0; s.Segment(); i++ {
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if len(s.Bytes()) != 1 || text[i] != s.Bytes()[0] {
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t.Errorf("#%d: expected %q got %q", i, text[i], s.Bytes()[0])
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}
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}
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// Check correct termination location and error.
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if i != okCount {
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t.Errorf("unexpected termination; expected %d tokens got %d", okCount, i)
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}
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err := s.Err()
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if err != testError {
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t.Fatalf("expected %q got %v", testError, err)
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}
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}
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// Test that Scan finishes if we have endless empty reads.
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type endlessZeros struct{}
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func (endlessZeros) Read(p []byte) (int, error) {
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return 0, nil
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}
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func TestBadReader(t *testing.T) {
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scanner := NewSegmenter(endlessZeros{})
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for scanner.Segment() {
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t.Fatal("read should fail")
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}
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err := scanner.Err()
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if err != io.ErrNoProgress {
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t.Errorf("unexpected error: %v", err)
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}
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}
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func TestSegmentAdvanceNegativeError(t *testing.T) {
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errorSplit := func(data []byte, atEOF bool) (advance int, token []byte, err error) {
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if atEOF {
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panic("didn't get enough data")
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}
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return -1, data[0:1], nil
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}
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// Read the data.
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const text = "abcdefghijklmnopqrstuvwxyz"
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buf := strings.NewReader(text)
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s := NewSegmenter(&slowReader{1, buf})
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// change to line segmenter for testing
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s.SetSegmenter(wrapSplitFuncAsSegmentFuncForTesting(errorSplit))
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s.Segment()
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err := s.Err()
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if err != ErrNegativeAdvance {
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t.Fatalf("expected %q got %v", testError, err)
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}
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}
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func TestSegmentAdvanceTooFarError(t *testing.T) {
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errorSplit := func(data []byte, atEOF bool) (advance int, token []byte, err error) {
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if atEOF {
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panic("didn't get enough data")
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}
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return len(data) + 10, data[0:1], nil
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}
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// Read the data.
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const text = "abcdefghijklmnopqrstuvwxyz"
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buf := strings.NewReader(text)
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s := NewSegmenter(&slowReader{1, buf})
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// change to line segmenter for testing
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s.SetSegmenter(wrapSplitFuncAsSegmentFuncForTesting(errorSplit))
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s.Segment()
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err := s.Err()
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if err != ErrAdvanceTooFar {
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t.Fatalf("expected %q got %v", testError, err)
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}
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}
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func TestSegmentLongTokens(t *testing.T) {
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// Read the data.
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text := bytes.Repeat([]byte("abcdefghijklmnop"), 257)
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buf := strings.NewReader(string(text))
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s := NewSegmenter(&slowReader{1, buf})
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// change to line segmenter for testing
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s.SetSegmenter(wrapSplitFuncAsSegmentFuncForTesting(bufio.ScanLines))
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for s.Segment() {
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line := s.Bytes()
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if !bytes.Equal(text, line) {
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t.Errorf("expected %s, got %s", text, line)
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}
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}
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err := s.Err()
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if err != nil {
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t.Fatalf("unexpected error; got %s", err)
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}
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}
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func TestSegmentLongTokensDontDouble(t *testing.T) {
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// Read the data.
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text := bytes.Repeat([]byte("abcdefghijklmnop"), 257)
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buf := strings.NewReader(string(text))
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s := NewSegmenter(&slowReader{1, buf})
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// change to line segmenter for testing
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s.SetSegmenter(wrapSplitFuncAsSegmentFuncForTesting(bufio.ScanLines))
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s.MaxTokenSize(6144)
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for s.Segment() {
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line := s.Bytes()
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if !bytes.Equal(text, line) {
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t.Errorf("expected %s, got %s", text, line)
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}
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}
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err := s.Err()
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if err != nil {
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t.Fatalf("unexpected error; got %s", err)
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}
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}
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