libgo/go/io/multi_test.go

   1 // Copyright 2010 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 io_test
   6
   7 import (
   8         "bytes"
   9         "crypto/sha1"
  10         "errors"
  11         "fmt"
  12         . "io"
  13         "io/ioutil"
  14         "runtime"
  15         "strings"
  16         "testing"
  17         "time"
  18 )
  19
  20 func TestMultiReader(t *testing.T) {
  21         var mr Reader
  22         var buf []byte
  23         nread := 0
  24         withFooBar := func(tests func()) {
  25                 r1 := strings.NewReader("foo ")
  26                 r2 := strings.NewReader("")
  27                 r3 := strings.NewReader("bar")
  28                 mr = MultiReader(r1, r2, r3)
  29                 buf = make([]byte, 20)
  30                 tests()
  31         }
  32         expectRead := func(size int, expected string, eerr error) {
  33                 nread++
  34                 n, gerr := mr.Read(buf[0:size])
  35                 if n != len(expected) {
  36                         t.Errorf("#%d, expected %d bytes; got %d",
  37                                 nread, len(expected), n)
  38                 }
  39                 got := string(buf[0:n])
  40                 if got != expected {
  41                         t.Errorf("#%d, expected %q; got %q",
  42                                 nread, expected, got)
  43                 }
  44                 if gerr != eerr {
  45                         t.Errorf("#%d, expected error %v; got %v",
  46                                 nread, eerr, gerr)
  47                 }
  48                 buf = buf[n:]
  49         }
  50         withFooBar(func() {
  51                 expectRead(2, "fo", nil)
  52                 expectRead(5, "o ", nil)
  53                 expectRead(5, "bar", nil)
  54                 expectRead(5, "", EOF)
  55         })
  56         withFooBar(func() {
  57                 expectRead(4, "foo ", nil)
  58                 expectRead(1, "b", nil)
  59                 expectRead(3, "ar", nil)
  60                 expectRead(1, "", EOF)
  61         })
  62         withFooBar(func() {
  63                 expectRead(5, "foo ", nil)
  64         })
  65 }
  66
  67 func TestMultiWriter(t *testing.T) {
  68         sink := new(bytes.Buffer)
  69         // Hide bytes.Buffer's WriteString method:
  70         testMultiWriter(t, struct {
  71                 Writer
  72                 fmt.Stringer
  73         }{sink, sink})
  74 }
  75
  76 func TestMultiWriter_String(t *testing.T) {
  77         testMultiWriter(t, new(bytes.Buffer))
  78 }
  79
  80 // test that a multiWriter.WriteString calls results in at most 1 allocation,
  81 // even if multiple targets don't support WriteString.
  82 func TestMultiWriter_WriteStringSingleAlloc(t *testing.T) {
  83         t.Skip("skipping on gccgo until we have escape analysis")
  84         var sink1, sink2 bytes.Buffer
  85         type simpleWriter struct { // hide bytes.Buffer's WriteString
  86                 Writer
  87         }
  88         mw := MultiWriter(simpleWriter{&sink1}, simpleWriter{&sink2})
  89         allocs := int(testing.AllocsPerRun(1000, func() {
  90                 WriteString(mw, "foo")
  91         }))
  92         if allocs != 1 {
  93                 t.Errorf("num allocations = %d; want 1", allocs)
  94         }
  95 }
  96
  97 type writeStringChecker struct{ called bool }
  98
  99 func (c *writeStringChecker) WriteString(s string) (n int, err error) {
 100         c.called = true
 101         return len(s), nil
 102 }
 103
 104 func (c *writeStringChecker) Write(p []byte) (n int, err error) {
 105         return len(p), nil
 106 }
 107
 108 func TestMultiWriter_StringCheckCall(t *testing.T) {
 109         var c writeStringChecker
 110         mw := MultiWriter(&c)
 111         WriteString(mw, "foo")
 112         if !c.called {
 113                 t.Error("did not see WriteString call to writeStringChecker")
 114         }
 115 }
 116
 117 func testMultiWriter(t *testing.T, sink interface {
 118         Writer
 119         fmt.Stringer
 120 }) {
 121         sha1 := sha1.New()
 122         mw := MultiWriter(sha1, sink)
 123
 124         sourceString := "My input text."
 125         source := strings.NewReader(sourceString)
 126         written, err := Copy(mw, source)
 127
 128         if written != int64(len(sourceString)) {
 129                 t.Errorf("short write of %d, not %d", written, len(sourceString))
 130         }
 131
 132         if err != nil {
 133                 t.Errorf("unexpected error: %v", err)
 134         }
 135
 136         sha1hex := fmt.Sprintf("%x", sha1.Sum(nil))
 137         if sha1hex != "01cb303fa8c30a64123067c5aa6284ba7ec2d31b" {
 138                 t.Error("incorrect sha1 value")
 139         }
 140
 141         if sink.String() != sourceString {
 142                 t.Errorf("expected %q; got %q", sourceString, sink.String())
 143         }
 144 }
 145
 146 // Test that MultiReader copies the input slice and is insulated from future modification.
 147 func TestMultiReaderCopy(t *testing.T) {
 148         slice := []Reader{strings.NewReader("hello world")}
 149         r := MultiReader(slice...)
 150         slice[0] = nil
 151         data, err := ioutil.ReadAll(r)
 152         if err != nil || string(data) != "hello world" {
 153                 t.Errorf("ReadAll() = %q, %v, want %q, nil", data, err, "hello world")
 154         }
 155 }
 156
 157 // Test that MultiWriter copies the input slice and is insulated from future modification.
 158 func TestMultiWriterCopy(t *testing.T) {
 159         var buf bytes.Buffer
 160         slice := []Writer{&buf}
 161         w := MultiWriter(slice...)
 162         slice[0] = nil
 163         n, err := w.Write([]byte("hello world"))
 164         if err != nil || n != 11 {
 165                 t.Errorf("Write(`hello world`) = %d, %v, want 11, nil", n, err)
 166         }
 167         if buf.String() != "hello world" {
 168                 t.Errorf("buf.String() = %q, want %q", buf.String(), "hello world")
 169         }
 170 }
 171
 172 // readerFunc is an io.Reader implemented by the underlying func.
 173 type readerFunc func(p []byte) (int, error)
 174
 175 func (f readerFunc) Read(p []byte) (int, error) {
 176         return f(p)
 177 }
 178
 179 // Test that MultiReader properly flattens chained multiReaders when Read is called
 180 func TestMultiReaderFlatten(t *testing.T) {
 181         pc := make([]uintptr, 1000) // 1000 should fit the full stack
 182         var myDepth = runtime.Callers(0, pc)
 183         var readDepth int // will contain the depth from which fakeReader.Read was called
 184         var r Reader = MultiReader(readerFunc(func(p []byte) (int, error) {
 185                 readDepth = runtime.Callers(1, pc)
 186                 return 0, errors.New("irrelevant")
 187         }))
 188
 189         // chain a bunch of multiReaders
 190         for i := 0; i < 100; i++ {
 191                 r = MultiReader(r)
 192         }
 193
 194         r.Read(nil) // don't care about errors, just want to check the call-depth for Read
 195
 196         if readDepth != myDepth+2 { // 2 should be multiReader.Read and fakeReader.Read
 197                 t.Errorf("multiReader did not flatten chained multiReaders: expected readDepth %d, got %d",
 198                         myDepth+2, readDepth)
 199         }
 200 }
 201
 202 // byteAndEOFReader is a Reader which reads one byte (the underlying
 203 // byte) and io.EOF at once in its Read call.
 204 type byteAndEOFReader byte
 205
 206 func (b byteAndEOFReader) Read(p []byte) (n int, err error) {
 207         if len(p) == 0 {
 208                 // Read(0 bytes) is useless. We expect no such useless
 209                 // calls in this test.
 210                 panic("unexpected call")
 211         }
 212         p[0] = byte(b)
 213         return 1, EOF
 214 }
 215
 216 // This used to yield bytes forever; issue 16795.
 217 func TestMultiReaderSingleByteWithEOF(t *testing.T) {
 218         got, err := ioutil.ReadAll(LimitReader(MultiReader(byteAndEOFReader('a'), byteAndEOFReader('b')), 10))
 219         if err != nil {
 220                 t.Fatal(err)
 221         }
 222         const want = "ab"
 223         if string(got) != want {
 224                 t.Errorf("got %q; want %q", got, want)
 225         }
 226 }
 227
 228 // Test that a reader returning (n, EOF) at the end of an MultiReader
 229 // chain continues to return EOF on its final read, rather than
 230 // yielding a (0, EOF).
 231 func TestMultiReaderFinalEOF(t *testing.T) {
 232         r := MultiReader(bytes.NewReader(nil), byteAndEOFReader('a'))
 233         buf := make([]byte, 2)
 234         n, err := r.Read(buf)
 235         if n != 1 || err != EOF {
 236                 t.Errorf("got %v, %v; want 1, EOF", n, err)
 237         }
 238 }
 239
 240 func TestMultiReaderFreesExhaustedReaders(t *testing.T) {
 241         if runtime.Compiler == "gccgo" {
 242                 t.Skip("skipping finalizer test on gccgo with conservative GC")
 243         }
 244
 245         var mr Reader
 246         closed := make(chan struct{})
 247         {
 248                 buf1 := bytes.NewReader([]byte("foo"))
 249                 buf2 := bytes.NewReader([]byte("bar"))
 250                 mr = MultiReader(buf1, buf2)
 251                 runtime.SetFinalizer(buf1, func(*bytes.Reader) {
 252                         close(closed)
 253                 })
 254         }
 255
 256         buf := make([]byte, 4)
 257         if n, err := ReadFull(mr, buf); err != nil || string(buf) != "foob" {
 258                 t.Fatalf(`ReadFull = %d (%q), %v; want 3, "foo", nil`, n, buf[:n], err)
 259         }
 260
 261         runtime.GC()
 262         select {
 263         case <-closed:
 264         case <-time.After(5 * time.Second):
 265                 t.Fatal("timeout waiting for collection of buf1")
 266         }
 267
 268         if n, err := ReadFull(mr, buf[:2]); err != nil || string(buf[:2]) != "ar" {
 269                 t.Fatalf(`ReadFull = %d (%q), %v; want 2, "ar", nil`, n, buf[:n], err)
 270         }
 271 }
 272
 273 func TestInterleavedMultiReader(t *testing.T) {
 274         r1 := strings.NewReader("123")
 275         r2 := strings.NewReader("45678")
 276
 277         mr1 := MultiReader(r1, r2)
 278         mr2 := MultiReader(mr1)
 279
 280         buf := make([]byte, 4)
 281
 282         // Have mr2 use mr1's []Readers.
 283         // Consume r1 (and clear it for GC to handle) and consume part of r2.
 284         n, err := ReadFull(mr2, buf)
 285         if got := string(buf[:n]); got != "1234" || err != nil {
 286                 t.Errorf(`ReadFull(mr2) = (%q, %v), want ("1234", nil)`, got, err)
 287         }
 288
 289         // Consume the rest of r2 via mr1.
 290         // This should not panic even though mr2 cleared r1.
 291         n, err = ReadFull(mr1, buf)
 292         if got := string(buf[:n]); got != "5678" || err != nil {
 293                 t.Errorf(`ReadFull(mr1) = (%q, %v), want ("5678", nil)`, got, err)
 294         }
 295 }