if ok1 || ok2 {
			return ok1 && ok2
		}
		return x == y
	}
	for _, v := range vectors {
		t.Run(path.Base(v.file), func(t *testing.T) {
			const maxSize = 10 << 10 // 10KiB
			buf := new(bytes.Buffer)
			tw := NewWriter(iotest.TruncateWriter(buf, maxSize))

			for i, tf := range v.tests {
				switch tf := tf.(type) {
				case testHeader:
					err := tw.WriteHeader(&tf.hdr)
					if !equalError(err, tf.wantErr) {