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// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package io_test
import (
"bytes"
"crypto/sha1"
"errors"
"fmt"
. "io"
"runtime"
"strings"
"testing"
"time"
)
func TestMultiReader(t *testing.T) {
var mr Reader
var buf []byte
nread := 0
withFooBar := func(tests func()) {
r1 := strings.NewReader("foo ")
r2 := strings.NewReader("")
r3 := strings.NewReader("bar")
mr = MultiReader(r1, r2, r3)
buf = make([]byte, 20)
tests()
}
expectRead := func(size int, expected string, eerr error) {
nread++
n, gerr := mr.Read(buf[0:size])
if n != len(expected) {
t.Errorf("#%d, expected %d bytes; got %d",
nread, len(expected), n)
}
got := string(buf[0:n])
if got != expected {
t.Errorf("#%d, expected %q; got %q",
nread, expected, got)
}
if gerr != eerr {
t.Errorf("#%d, expected error %v; got %v",
nread, eerr, gerr)
}
buf = buf[n:]
}
withFooBar(func() {
expectRead(2, "fo", nil)
expectRead(5, "o ", nil)
expectRead(5, "bar", nil)
expectRead(5, "", EOF)
})
withFooBar(func() {
expectRead(4, "foo ", nil)
expectRead(1, "b", nil)
expectRead(3, "ar", nil)
expectRead(1, "", EOF)
})
withFooBar(func() {
expectRead(5, "foo ", nil)
})
}
func TestMultiReaderAsWriterTo(t *testing.T) {
mr := MultiReader(
strings.NewReader("foo "),
MultiReader( // Tickle the buffer reusing codepath
strings.NewReader(""),
strings.NewReader("bar"),
),
)
mrAsWriterTo, ok := mr.(WriterTo)
if !ok {
t.Fatalf("expected cast to WriterTo to succeed")
}
sink := &strings.Builder{}
n, err := mrAsWriterTo.WriteTo(sink)
if err != nil {
t.Fatalf("expected no error; got %v", err)
}
if n != 7 {
t.Errorf("expected read 7 bytes; got %d", n)
}
if result := sink.String(); result != "foo bar" {
t.Errorf(`expected "foo bar"; got %q`, result)
}
}
func TestMultiWriter(t *testing.T) {
sink := new(bytes.Buffer)
// Hide bytes.Buffer's WriteString method:
testMultiWriter(t, struct {
Writer
fmt.Stringer
}{sink, sink})
}
func TestMultiWriter_String(t *testing.T) {
testMultiWriter(t, new(bytes.Buffer))
}
// Test that a multiWriter.WriteString calls results in at most 1 allocation,
// even if multiple targets don't support WriteString.
func TestMultiWriter_WriteStringSingleAlloc(t *testing.T) {
var sink1, sink2 bytes.Buffer
type simpleWriter struct { // hide bytes.Buffer's WriteString
Writer
}
mw := MultiWriter(simpleWriter{&sink1}, simpleWriter{&sink2})
allocs := int(testing.AllocsPerRun(1000, func() {
WriteString(mw, "foo")
}))
if allocs != 1 {
t.Errorf("num allocations = %d; want 1", allocs)
}
}
type writeStringChecker struct{ called bool }
func (c *writeStringChecker) WriteString(s string) (n int, err error) {
c.called = true
return len(s), nil
}
func (c *writeStringChecker) Write(p []byte) (n int, err error) {
return len(p), nil
}
func TestMultiWriter_StringCheckCall(t *testing.T) {
var c writeStringChecker
mw := MultiWriter(&c)
WriteString(mw, "foo")
if !c.called {
t.Error("did not see WriteString call to writeStringChecker")
}
}
func testMultiWriter(t *testing.T, sink interface {
Writer
fmt.Stringer
}) {
sha1 := sha1.New()
mw := MultiWriter(sha1, sink)
sourceString := "My input text."
source := strings.NewReader(sourceString)
written, err := Copy(mw, source)
if written != int64(len(sourceString)) {
t.Errorf("short write of %d, not %d", written, len(sourceString))
}
if err != nil {
t.Errorf("unexpected error: %v", err)
}
sha1hex := fmt.Sprintf("%x", sha1.Sum(nil))
if sha1hex != "01cb303fa8c30a64123067c5aa6284ba7ec2d31b" {
t.Error("incorrect sha1 value")
}
if sink.String() != sourceString {
t.Errorf("expected %q; got %q", sourceString, sink.String())
}
}
// writerFunc is a Writer implemented by the underlying func.
type writerFunc func(p []byte) (int, error)
func (f writerFunc) Write(p []byte) (int, error) {
return f(p)
}
// Test that MultiWriter properly flattens chained multiWriters.
func TestMultiWriterSingleChainFlatten(t *testing.T) {
pc := make([]uintptr, 1000) // 1000 should fit the full stack
n := runtime.Callers(0, pc)
var myDepth = callDepth(pc[:n])
var writeDepth int // will contain the depth from which writerFunc.Writer was called
var w Writer = MultiWriter(writerFunc(func(p []byte) (int, error) {
n := runtime.Callers(1, pc)
writeDepth += callDepth(pc[:n])
return 0, nil
}))
mw := w
// chain a bunch of multiWriters
for i := 0; i < 100; i++ {
mw = MultiWriter(w)
}
mw = MultiWriter(w, mw, w, mw)
mw.Write(nil) // don't care about errors, just want to check the call-depth for Write
if writeDepth != 4*(myDepth+2) { // 2 should be multiWriter.Write and writerFunc.Write
t.Errorf("multiWriter did not flatten chained multiWriters: expected writeDepth %d, got %d",
4*(myDepth+2), writeDepth)
}
}
func TestMultiWriterError(t *testing.T) {
f1 := writerFunc(func(p []byte) (int, error) {
return len(p) / 2, ErrShortWrite
})
f2 := writerFunc(func(p []byte) (int, error) {
t.Errorf("MultiWriter called f2.Write")
return len(p), nil
})
w := MultiWriter(f1, f2)
n, err := w.Write(make([]byte, 100))
if n != 50 || err != ErrShortWrite {
t.Errorf("Write = %d, %v, want 50, ErrShortWrite", n, err)
}
}
// Test that MultiReader copies the input slice and is insulated from future modification.
func TestMultiReaderCopy(t *testing.T) {
slice := []Reader{strings.NewReader("hello world")}
r := MultiReader(slice...)
slice[0] = nil
data, err := ReadAll(r)
if err != nil || string(data) != "hello world" {
t.Errorf("ReadAll() = %q, %v, want %q, nil", data, err, "hello world")
}
}
// Test that MultiWriter copies the input slice and is insulated from future modification.
func TestMultiWriterCopy(t *testing.T) {
var buf strings.Builder
slice := []Writer{&buf}
w := MultiWriter(slice...)
slice[0] = nil
n, err := w.Write([]byte("hello world"))
if err != nil || n != 11 {
t.Errorf("Write(`hello world`) = %d, %v, want 11, nil", n, err)
}
if buf.String() != "hello world" {
t.Errorf("buf.String() = %q, want %q", buf.String(), "hello world")
}
}
// readerFunc is a Reader implemented by the underlying func.
type readerFunc func(p []byte) (int, error)
func (f readerFunc) Read(p []byte) (int, error) {
return f(p)
}
// callDepth returns the logical call depth for the given PCs.
func callDepth(callers []uintptr) (depth int) {
frames := runtime.CallersFrames(callers)
more := true
for more {
_, more = frames.Next()
depth++
}
return
}
// Test that MultiReader properly flattens chained multiReaders when Read is called
func TestMultiReaderFlatten(t *testing.T) {
pc := make([]uintptr, 1000) // 1000 should fit the full stack
n := runtime.Callers(0, pc)
var myDepth = callDepth(pc[:n])
var readDepth int // will contain the depth from which fakeReader.Read was called
var r Reader = MultiReader(readerFunc(func(p []byte) (int, error) {
n := runtime.Callers(1, pc)
readDepth = callDepth(pc[:n])
return 0, errors.New("irrelevant")
}))
// chain a bunch of multiReaders
for i := 0; i < 100; i++ {
r = MultiReader(r)
}
r.Read(nil) // don't care about errors, just want to check the call-depth for Read
if readDepth != myDepth+2 { // 2 should be multiReader.Read and fakeReader.Read
t.Errorf("multiReader did not flatten chained multiReaders: expected readDepth %d, got %d",
myDepth+2, readDepth)
}
}
// byteAndEOFReader is a Reader which reads one byte (the underlying
// byte) and EOF at once in its Read call.
type byteAndEOFReader byte
func (b byteAndEOFReader) Read(p []byte) (n int, err error) {
if len(p) == 0 {
// Read(0 bytes) is useless. We expect no such useless
// calls in this test.
panic("unexpected call")
}
p[0] = byte(b)
return 1, EOF
}
// This used to yield bytes forever; issue 16795.
func TestMultiReaderSingleByteWithEOF(t *testing.T) {
got, err := ReadAll(LimitReader(MultiReader(byteAndEOFReader('a'), byteAndEOFReader('b')), 10))
if err != nil {
t.Fatal(err)
}
const want = "ab"
if string(got) != want {
t.Errorf("got %q; want %q", got, want)
}
}
// Test that a reader returning (n, EOF) at the end of a MultiReader
// chain continues to return EOF on its final read, rather than
// yielding a (0, EOF).
func TestMultiReaderFinalEOF(t *testing.T) {
r := MultiReader(bytes.NewReader(nil), byteAndEOFReader('a'))
buf := make([]byte, 2)
n, err := r.Read(buf)
if n != 1 || err != EOF {
t.Errorf("got %v, %v; want 1, EOF", n, err)
}
}
func TestMultiReaderFreesExhaustedReaders(t *testing.T) {
var mr Reader
closed := make(chan struct{})
// The closure ensures that we don't have a live reference to buf1
// on our stack after MultiReader is inlined (Issue 18819). This
// is a work around for a limitation in liveness analysis.
func() {
buf1 := bytes.NewReader([]byte("foo"))
buf2 := bytes.NewReader([]byte("bar"))
mr = MultiReader(buf1, buf2)
runtime.SetFinalizer(buf1, func(*bytes.Reader) {
close(closed)
})
}()
buf := make([]byte, 4)
if n, err := ReadFull(mr, buf); err != nil || string(buf) != "foob" {
t.Fatalf(`ReadFull = %d (%q), %v; want 3, "foo", nil`, n, buf[:n], err)
}
runtime.GC()
select {
case <-closed:
case <-time.After(5 * time.Second):
t.Fatal("timeout waiting for collection of buf1")
}
if n, err := ReadFull(mr, buf[:2]); err != nil || string(buf[:2]) != "ar" {
t.Fatalf(`ReadFull = %d (%q), %v; want 2, "ar", nil`, n, buf[:n], err)
}
}
func TestInterleavedMultiReader(t *testing.T) {
r1 := strings.NewReader("123")
r2 := strings.NewReader("45678")
mr1 := MultiReader(r1, r2)
mr2 := MultiReader(mr1)
buf := make([]byte, 4)
// Have mr2 use mr1's []Readers.
// Consume r1 (and clear it for GC to handle) and consume part of r2.
n, err := ReadFull(mr2, buf)
if got := string(buf[:n]); got != "1234" || err != nil {
t.Errorf(`ReadFull(mr2) = (%q, %v), want ("1234", nil)`, got, err)
}
// Consume the rest of r2 via mr1.
// This should not panic even though mr2 cleared r1.
n, err = ReadFull(mr1, buf)
if got := string(buf[:n]); got != "5678" || err != nil {
t.Errorf(`ReadFull(mr1) = (%q, %v), want ("5678", nil)`, got, err)
}
}