fix buffer reset

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

util/buffer/seeker_buffer.go

@@ -6,8 +6,10 @@ import (
 )
 
 var _ interface {
-	io.ReadCloser
+	io.Reader
-	io.ReadSeeker
+	io.Seeker
+	io.Writer
+	io.Closer
 } = (*SeekerBuffer)(nil)
 
 // SeekerBuffer is a ReadWriteCloser that supports seeking. It's intended to
@@ -95,7 +97,7 @@ func (b *SeekerBuffer) Close() error {
 
 // Reset clears all the data out of the buffer and sets the read position to 0.
 func (b *SeekerBuffer) Reset() {
-	b.data = nil
+	b.data = b.data[:0]
 	b.pos = 0
 }
 

util/buffer/seeker_buffer_test.go

@@ -296,7 +296,7 @@ func TestSeekerBuffer_Reset(t *testing.T) {
 	buf.pos = 2
 
 	buf.Reset()
-	require.Nil(t, buf.data)
+	require.Equal(t, []byte{}, buf.data)
 	require.Equal(t, int64(0), buf.pos)
 }