Use NullSubstituteReferenceException on null obj

Author: Jason31569

src/NSubstitute/Extensions/ProtectedExtensions.cs

@@ -1,6 +1,7 @@
 using System.Reflection;
 using NSubstitute.Core;
 using NSubstitute.Core.Arguments;
+using NSubstitute.Exceptions;
 
 // Disable nullability for client API, so it does not affect clients.
 #nullable disable annotations
@@ -17,11 +18,11 @@ public static class ProtectedExtensions
     /// <param name="methodName">Name of the method.</param>
     /// <param name="args">The method arguments.</param>
     /// <returns>Result object from the method invocation.</returns>
-    /// <exception cref="System.ArgumentNullException">Substitute - Cannot mock null object</exception>
+    /// <exception cref="NSubstitute.Exceptions.NullSubstituteReferenceException">Substitute - Cannot mock null object</exception>
     /// <exception cref="System.ArgumentException">Must provide valid protected method name to mock - methodName</exception>
     public static object Protected<T>(this T obj, string methodName, params object[] args) where T : class
     {
-        if (obj == null) { throw new ArgumentNullException(nameof(obj), "Cannot mock null object"); }
+        if (obj == null) { throw new NullSubstituteReferenceException(); }
         if (string.IsNullOrWhiteSpace(methodName)) { throw new ArgumentException("Must provide valid protected method name to mock", nameof(methodName)); }
 
         IList<IArgumentSpecification> argTypes = SubstitutionContext.Current.ThreadContext.PeekAllArgumentSpecifications();
@@ -41,11 +42,11 @@ public static object Protected<T>(this T obj, string methodName, params object[]
     /// <param name="methodName">Name of the method.</param>
     /// <param name="args">The method arguments.</param>
     /// <returns>WhenCalled&lt;T&gt;.</returns>
-    /// <exception cref="System.ArgumentNullException">Substitute - Cannot mock null object</exception>
+    /// <exception cref="NSubstitute.Exceptions.NullSubstituteReferenceException">Substitute - Cannot mock null object</exception>
     /// <exception cref="System.ArgumentException">Must provide valid protected method name to mock - methodName</exception>
     public static WhenCalled<T> When<T>(this T obj, string methodName, params object[] args) where T : class
     {
-        if (obj == null) { throw new ArgumentNullException(nameof(obj), "Cannot mock null object"); }
+        if (obj == null) { throw new NullSubstituteReferenceException(); }
         if (string.IsNullOrWhiteSpace(methodName)) { throw new ArgumentException("Must provide valid protected method name to mock", nameof(methodName)); }
 
         IList<IArgumentSpecification> argTypes = SubstitutionContext.Current.ThreadContext.PeekAllArgumentSpecifications();