// 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 (
	. "io"
	"os"
	"strings"
	"testing"
)

func TestMultiReader(t *testing.T) {
	var mr Reader
	var buf []byte
	nread := 0
	withFooBar := func(tests func()) {
		r1 := strings.NewReader("foo ")
		r2 := strings.NewReader("bar")
		mr = MultiReader(r1, r2)
		buf = make([]byte, 20)
		tests()
	}
	expectRead := func(size int, expected string, eerr os.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, "", os.EOF)
	})
	withFooBar(func() {
		expectRead(4, "foo ", nil)
		expectRead(1, "b", nil)
		expectRead(3, "ar", nil)
		expectRead(1, "", os.EOF)
	})
	withFooBar(func() {
		expectRead(5, "foo ", nil)
	})
}