better ArgumentException serialization

src/Directory.Build.props

@@ -2,7 +2,7 @@
 <Project>
   <PropertyGroup>
     <NoWarn>CS1591;CS0649;xUnit1026</NoWarn>
-    <Version>6.20.0</Version>
+    <Version>6.21.0</Version>
     <AssemblyVersion>1.0.0</AssemblyVersion>
     <PackageTags>Json, Testing, Verify, Snapshot, Approvals</PackageTags>
     <Description>Enables verification of complex models and documents.</Description>

src/Verify.Tests/Tests.ThrowsArgumentException.verified.txt

@@ -0,0 +1,5 @@
+{
+  Type: 'ArgumentException',
+  Message: 'The Message',
+  ParamName: 'The parameter'
+}

src/Verify.Tests/Tests.ThrowsInheritedArgumentException.verified.txt

@@ -0,0 +1,5 @@
+{
+  Type: 'ArgumentNullException',
+  Message: 'The Message',
+  ParamName: 'The parameter'
+}

src/Verify.Tests/Tests.cs

@@ -103,6 +103,28 @@ static void MethodThatThrows()
         throw new Exception("The Message");
     }
 
+    [Fact]
+    public Task ThrowsArgumentException()
+    {
+        return Verifier.Throws(MethodThatThrowsArgumentException);
+    }
+
+    static void MethodThatThrowsArgumentException()
+    {
+        throw new ArgumentException("The Message", "The parameter");
+    }
+
+    [Fact]
+    public Task ThrowsInheritedArgumentException()
+    {
+        return Verifier.Throws(MethodThatThrowsArgumentNullException);
+    }
+
+    static void MethodThatThrowsArgumentNullException()
+    {
+        throw new ArgumentNullException("The parameter", "The Message");
+    }
+
     [Fact]
     public Task ThrowsAggregate()
     {

src/Verify/Serialization/CustomContractResolver.cs

@@ -113,6 +113,8 @@ string ResolveDictionaryKey(JsonDictionaryContract contract, string value)
         return value;
     }
 
+    FieldInfo exceptionMessageField = typeof(Exception).GetField("_message", BindingFlags.Instance | BindingFlags.NonPublic)!;
+
     protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization serialization)
     {
         var property = base.CreateProperty(member, serialization);
@@ -124,6 +126,14 @@ protected override JsonProperty CreateProperty(MemberInfo member, MemberSerializ
             return property;
         }
 
+        if (member.Name == "Message")
+        {
+            if (member.DeclaringType == typeof(ArgumentException))
+            {
+                valueProvider = new ReflectionValueProvider(exceptionMessageField);
+            }
+        }
+
         if (propertyType.IsException())
         {
             property.TypeNameHandling = TypeNameHandling.All;