Added Custom exception to flag a model rule violation

Author: antoineatstariongroup

SysML2.NET/Exceptions/SysML2ModelException.cs

@@ -0,0 +1,48 @@
+// -------------------------------------------------------------------------------------------------
+// <copyright file="SysMl2ModelException.cs" company="Starion Group S.A.">
+// 
+//   Copyright 2022-2026 Starion Group S.A.
+// 
+//   Licensed under the Apache License, Version 2.0 (the "License");
+//   you may not use this file except in compliance with the License.
+//   You may obtain a copy of the License at
+// 
+//        http://www.apache.org/licenses/LICENSE-2.0
+// 
+//    Unless required by applicable law or agreed to in writing, software
+//    distributed under the License is distributed on an "AS IS" BASIS,
+//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//    See the License for the specific language governing permissions and
+//    limitations under the License.
+// 
+// </copyright>
+// ------------------------------------------------------------------------------------------------
+
+namespace SysML2.NET.Exceptions
+{
+    using System;
+    
+    /// <summary>
+    /// The <see cref="SysMl2ModelException"/> provide custom exception that should be used when a SysML 2 rule violation appears into a model 
+    /// </summary>
+    public class SysMl2ModelException: Exception
+    {
+        /// <summary>Initializes a new instance of the <see cref="SysMl2ModelException" /> class.</summary>
+        public SysMl2ModelException()
+        {
+        }
+
+        /// <summary>Initializes a new instance of the <see cref="SysMl2ModelException" /> class with a specified error message.</summary>
+        /// <param name="message">The message that describes the error.</param>
+        public SysMl2ModelException(string message) : base(message)
+        {
+        }
+
+        /// <summary>Initializes a new instance of the <see cref="SysMl2ModelException" /> class with a specified error message and a reference to the inner exception that is the cause of this exception.</summary>
+        /// <param name="message">The error message that explains the reason for the exception.</param>
+        /// <param name="innerException">The exception that is the cause of the current exception, or a null reference (<see langword="Nothing" /> in Visual Basic) if no inner exception is specified.</param>
+        public SysMl2ModelException(string message, Exception innerException) : base(message, innerException)
+        {
+        }
+    }
+}

SysML2.NET/Extend/OwningMembershipExtensions.cs

@@ -27,6 +27,7 @@ namespace SysML2.NET.Core.POCO.Root.Namespaces
     using SysML2.NET.Core.Root.Namespaces;
     using SysML2.NET.Core.POCO.Root.Annotations;
     using SysML2.NET.Core.POCO.Root.Elements;
+    using SysML2.NET.Exceptions;
 
     /// <summary>
     /// The <see cref="OwningMembershipExtensions"/> class provides extensions methods for
@@ -45,7 +46,12 @@ internal static class OwningMembershipExtensions
         /// </returns>
         internal static IElement ComputeOwnedMemberElement(this IOwningMembership owningMembershipSubject)
         {
-            return owningMembershipSubject == null ? throw new ArgumentNullException(nameof(owningMembershipSubject)) : owningMembershipSubject.OwnedRelatedElement.Single();
+            if (owningMembershipSubject == null)
+            {
+                throw new ArgumentNullException(nameof(owningMembershipSubject));
+            }
+
+            return owningMembershipSubject.OwnedRelatedElement.Count != 1 ? throw new SysMl2ModelException($"{nameof(owningMembershipSubject)} must have exactly one related element") : owningMembershipSubject.OwnedRelatedElement.Single();
         }
 
         /// <summary>