fix diff round-trip comparison

pkg/readers/pgsql/reader_test.go

@@ -2,6 +2,7 @@ package pgsql
 
 import (
 	"os"
+	"reflect"
 	"testing"
 
 	"git.warky.dev/wdevs/relspecgo/pkg/models"
@@ -359,6 +360,14 @@ func TestDeriveRelationship(t *testing.T) {
 		t.Errorf("Expected ToTable 'users', got '%s'", rel.ToTable)
 	}
 
+	if !reflect.DeepEqual(rel.FromColumns, []string{"user_id"}) {
+		t.Errorf("Expected FromColumns [user_id], got %v", rel.FromColumns)
+	}
+
+	if !reflect.DeepEqual(rel.ToColumns, []string{"id"}) {
+		t.Errorf("Expected ToColumns [id], got %v", rel.ToColumns)
+	}
+
 	if rel.ForeignKey != "fk_orders_user_id" {
 		t.Errorf("Expected ForeignKey 'fk_orders_user_id', got '%s'", rel.ForeignKey)
 	}