package readers import (	"bytes"	"io"	"testing" 	"github.com/stretchr/testify/assert"	"github.com/stretchr/testify/require") func TestRepeatableReader(t *testing.T) {	var dst []byte	var n int	var pos int64	var err error 	b := []byte("Testbuffer")	buf := bytes.NewBuffer(b)	r := NewRepeatableReader(buf) 	dst = make([]byte, 100)	n, err = r.Read(dst)	assert.Nil(t, err)	assert.Equal(t, 10, n)	require.Equal(t, b, dst[0:10]) 	// Test read EOF	n, err = r.Read(dst)	assert.Equal(t, io.EOF, err)	assert.Equal(t, 0, n) 	// Test Seek Back to start	dst = make([]byte, 10)	pos, err = r.Seek(0, io.SeekStart)	assert.Nil(t, err)	require.Equal(t, 0, int(pos)) 	n, err = r.Read(dst)	assert.Nil(t, err)	assert.Equal(t, 10, n)	require.Equal(t, b, dst) 	// Test partial read	buf = bytes.NewBuffer(b)	r = NewRepeatableReader(buf)	dst = make([]byte, 5)	n, err = r.Read(dst)	assert.Nil(t, err)	assert.Equal(t, 5, n)	require.Equal(t, b[0:5], dst)	n, err = r.Read(dst)	assert.Nil(t, err)	assert.Equal(t, 5, n)	require.Equal(t, b[5:], dst) 	// Test Seek	buf = bytes.NewBuffer(b)	r = NewRepeatableReader(buf)	// Should not allow seek past cache index	pos, err = r.Seek(5, io.SeekCurrent)	assert.NotNil(t, err)	assert.Equal(t, "fs.RepeatableReader.Seek: offset is unavailable", err.Error())	assert.Equal(t, 0, int(pos)) 	// Should not allow seek to negative position start	pos, err = r.Seek(-1, io.SeekCurrent)	assert.NotNil(t, err)	assert.Equal(t, "fs.RepeatableReader.Seek: negative position", err.Error())	assert.Equal(t, 0, int(pos)) 	// Should not allow seek with invalid whence	pos, err = r.Seek(0, 3)	assert.NotNil(t, err)	assert.Equal(t, "fs.RepeatableReader.Seek: invalid whence", err.Error())	assert.Equal(t, 0, int(pos)) 	// Should seek from index with io.SeekCurrent(1) whence	dst = make([]byte, 5)	_, _ = r.Read(dst)	pos, err = r.Seek(-3, io.SeekCurrent)	assert.Nil(t, err)	require.Equal(t, 2, int(pos))	pos, err = r.Seek(1, io.SeekCurrent)	assert.Nil(t, err)	require.Equal(t, 3, int(pos)) 	// Should seek from cache end with io.SeekEnd(2) whence	pos, err = r.Seek(-3, io.SeekEnd)	assert.Nil(t, err)	require.Equal(t, 2, int(pos)) 	// Should read from seek position and past it	dst = make([]byte, 5)	n, err = io.ReadFull(r, dst)	assert.Nil(t, err)	assert.Equal(t, 5, n)	assert.Equal(t, b[2:7], dst) }