feat: full NFSv4.2 server and client in pure Go

Assisted-by: GLM 5.3 Flash

internal/nfsclient/nattr_extra_test.go

@@ -0,0 +1,22 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
+package nfsclient
+
+import (
+	"strings"
+	"testing"
+
+	"sourcedock.dev/petrbalvin/nfs/internal/nfs4"
+)
+
+// The NFS error carries its status into text a caller can log.
+func TestNFSErrorText(t *testing.T) {
+	err := &NFSError{Status: nfs4.ErrNoEnt}
+	if !strings.Contains(err.Error(), "2") {
+		t.Fatalf("error text %q", err.Error())
+	}
+	if err.Error() == "" {
+		t.Fatal("empty error text")
+	}
+}