1 files changed, 379 insertions, 0 deletions
diff --git a/src/io/multi_test.go b/src/io/multi_test.go
new file mode 100644
index 0000000..7a24a8a
--- /dev/null
+++ b/src/io/multi_test.go
@@ -0,0 +1,379 @@
+// 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)
+	}
+}