memio - limitedbuffer_test.go

     1  package memio
     2  
     3  import (
     4  	"bytes"
     5  	"io"
     6  	"testing"
     7  )
     8  
     9  var (
    10  	_ io.Reader     = &LimitedBuffer{}
    11  	_ io.Writer     = &LimitedBuffer{}
    12  	_ io.WriterTo   = &LimitedBuffer{}
    13  	_ io.ReaderFrom = &LimitedBuffer{}
    14  	_ io.ReaderAt   = &LimitedBuffer{}
    15  	_ io.WriterAt   = &LimitedBuffer{}
    16  )
    17  
    18  func TestLimitedBufferWrite(t *testing.T) {
    19  	data := []byte("Beep")
    20  	writer := LimitedBuffer(data)[:0:4]
    21  	if n, err := writer.Write([]byte("J")); n != 1 {
    22  		t.Errorf("expecting to write 1 byte, wrote %d", n)
    23  		return
    24  	} else if err != nil {
    25  		t.Errorf("got error: %q", err.Error())
    26  		return
    27  	} else if string(data) != "Jeep" {
    28  		t.Errorf("expecting %q, got %q", "Jeep  ", string(data))
    29  		return
    30  	}
    31  	if n, err := writer.Write([]byte("ohn")); n != 3 {
    32  		t.Errorf("expecting to write 3 bytes, wrote %d", n)
    33  		return
    34  	} else if err != nil {
    35  		t.Errorf("got error: %q", err.Error())
    36  		return
    37  	} else if string(data) != "John" {
    38  		t.Errorf("expecting %q, got %q", "John  ", string(data))
    39  		return
    40  	}
    41  	if n, err := writer.Write([]byte("ny")); err != io.ErrShortBuffer {
    42  		t.Errorf("expecting io.ErrShortBuffer, got: %s", err)
    43  		return
    44  	} else if n != 0 {
    45  		t.Errorf("expecting to write 0 bytes, wrote %d", n)
    46  	}
    47  }
    48  
    49  type byteReader byte
    50  
    51  func (b byteReader) Read(p []byte) (int, error) {
    52  	if int(b) < len(p) {
    53  		p = p[:b]
    54  	}
    55  	for i := byte(0); i < byte(len(p)); i++ {
    56  		p[i] = i
    57  	}
    58  	return len(p), nil
    59  }
    60  
    61  func TestLimitedBufferReadFrom(t *testing.T) {
    62  	l := make(LimitedBuffer, 0, 30)
    63  	n, err := l.ReadFrom(byteReader(1))
    64  	if n != 30 {
    65  		t.Errorf("expecting to read 30 bytes, read %d", n)
    66  	} else if err != nil {
    67  		t.Errorf("go unexpected error: %s", err)
    68  	} else if !bytes.Equal(l, bytes.Repeat([]byte{0}, 30)) {
    69  		t.Errorf("expecting 30 0's, got %v", l)
    70  	}
    71  
    72  	l = l[:0]
    73  	n, err = l.ReadFrom(byteReader(2))
    74  	if n != 30 {
    75  		t.Errorf("expecting to read 30 bytes, read %d", n)
    76  	} else if err != nil {
    77  		t.Errorf("go unexpected error: %s", err)
    78  	} else if !bytes.Equal(l, bytes.Repeat([]byte{0, 1}, 15)) {
    79  		t.Errorf("expecting 15 [0, 1]'s, got %v", l)
    80  	}
    81  
    82  	l = l[:0]
    83  	n, err = l.ReadFrom(byteReader(3))
    84  	if n != 30 {
    85  		t.Errorf("expecting to read 30 bytes, read %d", n)
    86  	} else if err != nil {
    87  		t.Errorf("go unexpected error: %s", err)
    88  	} else if !bytes.Equal(l, bytes.Repeat([]byte{0, 1, 2}, 10)) {
    89  		t.Errorf("expecting 10 [0, 1, 2]'s, got %v", l)
    90  	}
    91  
    92  	l = l[:0]
    93  	n, err = l.ReadFrom(io.LimitReader(byteReader(4), 20))
    94  	if n != 20 {
    95  		t.Errorf("expecting to read 20 bytes, read %d", n)
    96  	} else if err != nil {
    97  		t.Errorf("go unexpected error: %s", err)
    98  	} else if !bytes.Equal(l, bytes.Repeat([]byte{0, 1, 2, 3}, 5)) {
    99  		t.Errorf("expecting 5 [0, 1, 2, 3]'s, got %v", l)
   100  	}
   101  }
   102