github.com/rsc/go@v0.0.0-20150416155037-e040fd465409/src/io/multi_test.go (about)

     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  	"fmt"
    11  	. "io"
    12  	"io/ioutil"
    13  	"strings"
    14  	"testing"
    15  )
    16  
    17  func TestMultiReader(t *testing.T) {
    18  	var mr Reader
    19  	var buf []byte
    20  	nread := 0
    21  	withFooBar := func(tests func()) {
    22  		r1 := strings.NewReader("foo ")
    23  		r2 := strings.NewReader("")
    24  		r3 := strings.NewReader("bar")
    25  		mr = MultiReader(r1, r2, r3)
    26  		buf = make([]byte, 20)
    27  		tests()
    28  	}
    29  	expectRead := func(size int, expected string, eerr error) {
    30  		nread++
    31  		n, gerr := mr.Read(buf[0:size])
    32  		if n != len(expected) {
    33  			t.Errorf("#%d, expected %d bytes; got %d",
    34  				nread, len(expected), n)
    35  		}
    36  		got := string(buf[0:n])
    37  		if got != expected {
    38  			t.Errorf("#%d, expected %q; got %q",
    39  				nread, expected, got)
    40  		}
    41  		if gerr != eerr {
    42  			t.Errorf("#%d, expected error %v; got %v",
    43  				nread, eerr, gerr)
    44  		}
    45  		buf = buf[n:]
    46  	}
    47  	withFooBar(func() {
    48  		expectRead(2, "fo", nil)
    49  		expectRead(5, "o ", nil)
    50  		expectRead(5, "bar", nil)
    51  		expectRead(5, "", EOF)
    52  	})
    53  	withFooBar(func() {
    54  		expectRead(4, "foo ", nil)
    55  		expectRead(1, "b", nil)
    56  		expectRead(3, "ar", nil)
    57  		expectRead(1, "", EOF)
    58  	})
    59  	withFooBar(func() {
    60  		expectRead(5, "foo ", nil)
    61  	})
    62  }
    63  
    64  func TestMultiWriter(t *testing.T) {
    65  	sha1 := sha1.New()
    66  	sink := new(bytes.Buffer)
    67  	mw := MultiWriter(sha1, sink)
    68  
    69  	sourceString := "My input text."
    70  	source := strings.NewReader(sourceString)
    71  	written, err := Copy(mw, source)
    72  
    73  	if written != int64(len(sourceString)) {
    74  		t.Errorf("short write of %d, not %d", written, len(sourceString))
    75  	}
    76  
    77  	if err != nil {
    78  		t.Errorf("unexpected error: %v", err)
    79  	}
    80  
    81  	sha1hex := fmt.Sprintf("%x", sha1.Sum(nil))
    82  	if sha1hex != "01cb303fa8c30a64123067c5aa6284ba7ec2d31b" {
    83  		t.Error("incorrect sha1 value")
    84  	}
    85  
    86  	if sink.String() != sourceString {
    87  		t.Errorf("expected %q; got %q", sourceString, sink.String())
    88  	}
    89  }
    90  
    91  // Test that MultiReader copies the input slice and is insulated from future modification.
    92  func TestMultiReaderCopy(t *testing.T) {
    93  	slice := []Reader{strings.NewReader("hello world")}
    94  	r := MultiReader(slice...)
    95  	slice[0] = nil
    96  	data, err := ioutil.ReadAll(r)
    97  	if err != nil || string(data) != "hello world" {
    98  		t.Errorf("ReadAll() = %q, %v, want %q, nil", data, err, "hello world")
    99  	}
   100  }
   101  
   102  // Test that MultiWriter copies the input slice and is insulated from future modification.
   103  func TestMultiWriterCopy(t *testing.T) {
   104  	var buf bytes.Buffer
   105  	slice := []Writer{&buf}
   106  	w := MultiWriter(slice...)
   107  	slice[0] = nil
   108  	n, err := w.Write([]byte("hello world"))
   109  	if err != nil || n != 11 {
   110  		t.Errorf("Write(`hello world`) = %d, %v, want 11, nil", n, err)
   111  	}
   112  	if buf.String() != "hello world" {
   113  		t.Errorf("buf.String() = %q, want %q", buf.String(), "hello world")
   114  	}
   115  }