1// Copyright 2012 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
5package strings_test
6
7import (
8	"bytes"
9	"fmt"
10	"io"
11	"io/ioutil"
12	"strings"
13	"sync"
14	"testing"
15)
16
17func TestReader(t *testing.T) {
18	r := strings.NewReader("0123456789")
19	tests := []struct {
20		off     int64
21		seek    int
22		n       int
23		want    string
24		wantpos int64
25		readerr error
26		seekerr string
27	}{
28		{seek: io.SeekStart, off: 0, n: 20, want: "0123456789"},
29		{seek: io.SeekStart, off: 1, n: 1, want: "1"},
30		{seek: io.SeekCurrent, off: 1, wantpos: 3, n: 2, want: "34"},
31		{seek: io.SeekStart, off: -1, seekerr: "strings.Reader.Seek: negative position"},
32		{seek: io.SeekStart, off: 1 << 33, wantpos: 1 << 33, readerr: io.EOF},
33		{seek: io.SeekCurrent, off: 1, wantpos: 1<<33 + 1, readerr: io.EOF},
34		{seek: io.SeekStart, n: 5, want: "01234"},
35		{seek: io.SeekCurrent, n: 5, want: "56789"},
36		{seek: io.SeekEnd, off: -1, n: 1, wantpos: 9, want: "9"},
37	}
38
39	for i, tt := range tests {
40		pos, err := r.Seek(tt.off, tt.seek)
41		if err == nil && tt.seekerr != "" {
42			t.Errorf("%d. want seek error %q", i, tt.seekerr)
43			continue
44		}
45		if err != nil && err.Error() != tt.seekerr {
46			t.Errorf("%d. seek error = %q; want %q", i, err.Error(), tt.seekerr)
47			continue
48		}
49		if tt.wantpos != 0 && tt.wantpos != pos {
50			t.Errorf("%d. pos = %d, want %d", i, pos, tt.wantpos)
51		}
52		buf := make([]byte, tt.n)
53		n, err := r.Read(buf)
54		if err != tt.readerr {
55			t.Errorf("%d. read = %v; want %v", i, err, tt.readerr)
56			continue
57		}
58		got := string(buf[:n])
59		if got != tt.want {
60			t.Errorf("%d. got %q; want %q", i, got, tt.want)
61		}
62	}
63}
64
65func TestReadAfterBigSeek(t *testing.T) {
66	r := strings.NewReader("0123456789")
67	if _, err := r.Seek(1<<31+5, io.SeekStart); err != nil {
68		t.Fatal(err)
69	}
70	if n, err := r.Read(make([]byte, 10)); n != 0 || err != io.EOF {
71		t.Errorf("Read = %d, %v; want 0, EOF", n, err)
72	}
73}
74
75func TestReaderAt(t *testing.T) {
76	r := strings.NewReader("0123456789")
77	tests := []struct {
78		off     int64
79		n       int
80		want    string
81		wanterr interface{}
82	}{
83		{0, 10, "0123456789", nil},
84		{1, 10, "123456789", io.EOF},
85		{1, 9, "123456789", nil},
86		{11, 10, "", io.EOF},
87		{0, 0, "", nil},
88		{-1, 0, "", "strings.Reader.ReadAt: negative offset"},
89	}
90	for i, tt := range tests {
91		b := make([]byte, tt.n)
92		rn, err := r.ReadAt(b, tt.off)
93		got := string(b[:rn])
94		if got != tt.want {
95			t.Errorf("%d. got %q; want %q", i, got, tt.want)
96		}
97		if fmt.Sprintf("%v", err) != fmt.Sprintf("%v", tt.wanterr) {
98			t.Errorf("%d. got error = %v; want %v", i, err, tt.wanterr)
99		}
100	}
101}
102
103func TestReaderAtConcurrent(t *testing.T) {
104	// Test for the race detector, to verify ReadAt doesn't mutate
105	// any state.
106	r := strings.NewReader("0123456789")
107	var wg sync.WaitGroup
108	for i := 0; i < 5; i++ {
109		wg.Add(1)
110		go func(i int) {
111			defer wg.Done()
112			var buf [1]byte
113			r.ReadAt(buf[:], int64(i))
114		}(i)
115	}
116	wg.Wait()
117}
118
119func TestEmptyReaderConcurrent(t *testing.T) {
120	// Test for the race detector, to verify a Read that doesn't yield any bytes
121	// is okay to use from multiple goroutines. This was our historic behavior.
122	// See golang.org/issue/7856
123	r := strings.NewReader("")
124	var wg sync.WaitGroup
125	for i := 0; i < 5; i++ {
126		wg.Add(2)
127		go func() {
128			defer wg.Done()
129			var buf [1]byte
130			r.Read(buf[:])
131		}()
132		go func() {
133			defer wg.Done()
134			r.Read(nil)
135		}()
136	}
137	wg.Wait()
138}
139
140func TestWriteTo(t *testing.T) {
141	const str = "0123456789"
142	for i := 0; i <= len(str); i++ {
143		s := str[i:]
144		r := strings.NewReader(s)
145		var b bytes.Buffer
146		n, err := r.WriteTo(&b)
147		if expect := int64(len(s)); n != expect {
148			t.Errorf("got %v; want %v", n, expect)
149		}
150		if err != nil {
151			t.Errorf("for length %d: got error = %v; want nil", len(s), err)
152		}
153		if b.String() != s {
154			t.Errorf("got string %q; want %q", b.String(), s)
155		}
156		if r.Len() != 0 {
157			t.Errorf("reader contains %v bytes; want 0", r.Len())
158		}
159	}
160}
161
162// tests that Len is affected by reads, but Size is not.
163func TestReaderLenSize(t *testing.T) {
164	r := strings.NewReader("abc")
165	io.CopyN(ioutil.Discard, r, 1)
166	if r.Len() != 2 {
167		t.Errorf("Len = %d; want 2", r.Len())
168	}
169	if r.Size() != 3 {
170		t.Errorf("Size = %d; want 3", r.Size())
171	}
172}
173
174func TestReaderReset(t *testing.T) {
175	r := strings.NewReader("世界")
176	if _, _, err := r.ReadRune(); err != nil {
177		t.Errorf("ReadRune: unexpected error: %v", err)
178	}
179
180	const want = "abcdef"
181	r.Reset(want)
182	if err := r.UnreadRune(); err == nil {
183		t.Errorf("UnreadRune: expected error, got nil")
184	}
185	buf, err := ioutil.ReadAll(r)
186	if err != nil {
187		t.Errorf("ReadAll: unexpected error: %v", err)
188	}
189	if got := string(buf); got != want {
190		t.Errorf("ReadAll: got %q, want %q", got, want)
191	}
192}
193
194func TestReaderZero(t *testing.T) {
195	if l := (&strings.Reader{}).Len(); l != 0 {
196		t.Errorf("Len: got %d, want 0", l)
197	}
198
199	if n, err := (&strings.Reader{}).Read(nil); n != 0 || err != io.EOF {
200		t.Errorf("Read: got %d, %v; want 0, io.EOF", n, err)
201	}
202
203	if n, err := (&strings.Reader{}).ReadAt(nil, 11); n != 0 || err != io.EOF {
204		t.Errorf("ReadAt: got %d, %v; want 0, io.EOF", n, err)
205	}
206
207	if b, err := (&strings.Reader{}).ReadByte(); b != 0 || err != io.EOF {
208		t.Errorf("ReadByte: got %d, %v; want 0, io.EOF", b, err)
209	}
210
211	if ch, size, err := (&strings.Reader{}).ReadRune(); ch != 0 || size != 0 || err != io.EOF {
212		t.Errorf("ReadRune: got %d, %d, %v; want 0, 0, io.EOF", ch, size, err)
213	}
214
215	if offset, err := (&strings.Reader{}).Seek(11, io.SeekStart); offset != 11 || err != nil {
216		t.Errorf("Seek: got %d, %v; want 11, nil", offset, err)
217	}
218
219	if s := (&strings.Reader{}).Size(); s != 0 {
220		t.Errorf("Size: got %d, want 0", s)
221	}
222
223	if (&strings.Reader{}).UnreadByte() == nil {
224		t.Errorf("UnreadByte: got nil, want error")
225	}
226
227	if (&strings.Reader{}).UnreadRune() == nil {
228		t.Errorf("UnreadRune: got nil, want error")
229	}
230
231	if n, err := (&strings.Reader{}).WriteTo(ioutil.Discard); n != 0 || err != nil {
232		t.Errorf("WriteTo: got %d, %v; want 0, nil", n, err)
233	}
234}
235