i := copy(b2, b)
	return b2[:i]
}

// WriteTo writes data to w until the buffer is drained or an error occurs.
// The return value n is the number of bytes written; it always fits into an
// int, but it is int64 to match the [io.WriterTo] interface. Any error
// encountered during the write is also returned.
func (b *Buffer) WriteTo(w io.Writer) (n int64, err error) {
	b.lastRead = opInvalid

				}
			case testWriteTo:
				f := &testFile{ops: tf.ops}
				got, err := fr.WriteTo(f)
				if _, ok := err.(testError); ok {
					t.Errorf("test %d.%d, WriteTo(): %v", i, j, err)
				} else if got != tf.wantCnt || err != tf.wantErr {
					t.Errorf("test %d.%d, WriteTo() = (%d, %v), want (%d, %v)", i, j, got, err, tf.wantCnt, tf.wantErr)
				}
				if len(f.ops) > 0 {

}

func TestWriteTo(t *testing.T) {
	var buf Buffer
	for i := 3; i < 30; i += 3 {
		s := fillBytes(t, "TestWriteTo (1)", &buf, "", 5, testBytes[:len(testBytes)/i])
		var b Buffer
		buf.WriteTo(&b)
		empty(t, "TestWriteTo (2)", &b, s, make([]byte, len(testString)))
	}
}

func TestWriteAppend(t *testing.T) {
	var got Buffer
	var want []byte
	for i := 0; i < 1000; i++ {