t.Fatal("expected error, got nil")
	}
	if buffered := wr.Buffered(); buffered != wantBuffered {
		t.Fatalf("Buffered = %v; want %v", buffered, wantBuffered)
	}
}

func BenchmarkReaderCopyOptimal(b *testing.B) {
	// Optimal case is where the underlying reader implements io.WriterTo
	srcBuf := bytes.NewBuffer(make([]byte, 8192))
	src := NewReader(srcBuf)
	dstBuf := new(bytes.Buffer)