From 1ca8f79a36ec1905803e2d86c325cc52354026f5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20St=C3=BChmer?=
 <3283596+samtrion@users.noreply.github.com>
Date: Tue, 3 Dec 2019 15:38:27 +0100
Subject: [PATCH] Improved support for `Nullable<T>` and `dynamic` parameters
 (#96)

---
 .../EnhancedStackTrace.Frames.cs              |  1 +
 src/Ben.Demystifier/ResolvedParameter.cs      |  7 +-
 src/Ben.Demystifier/TypeNameHelper.cs         | 13 +++-
 test/Ben.Demystifier.Test/MethodTests.cs      | 65 +++++++++++++++++++
 4 files changed, 83 insertions(+), 3 deletions(-)
 create mode 100644 test/Ben.Demystifier.Test/MethodTests.cs

diff --git a/src/Ben.Demystifier/EnhancedStackTrace.Frames.cs b/src/Ben.Demystifier/EnhancedStackTrace.Frames.cs
index ababbcf..988f628 100644
--- a/src/Ben.Demystifier/EnhancedStackTrace.Frames.cs
+++ b/src/Ben.Demystifier/EnhancedStackTrace.Frames.cs
@@ -563,6 +563,7 @@ namespace System.Diagnostics
                 Prefix = prefix,
                 Name = parameter.Name,
                 ResolvedType = parameterType,
+                IsDynamicType = parameter.IsDefined(typeof(DynamicAttribute), false)
             };
         }
 
diff --git a/src/Ben.Demystifier/ResolvedParameter.cs b/src/Ben.Demystifier/ResolvedParameter.cs
index d611b2e..2b4f5e5 100644
--- a/src/Ben.Demystifier/ResolvedParameter.cs
+++ b/src/Ben.Demystifier/ResolvedParameter.cs
@@ -12,6 +12,7 @@ namespace System.Diagnostics
         public Type ResolvedType { get; set; }
 
         public string Prefix { get; set; }
+        public bool IsDynamicType { get; set; }
 
         public override string ToString() => Append(new StringBuilder()).ToString();
 
@@ -23,7 +24,11 @@ namespace System.Diagnostics
                   .Append(" ");
             }
 
-            if (ResolvedType != null)
+            if (IsDynamicType)
+            {
+                sb.Append("dynamic");
+            }
+            else if (ResolvedType != null)
             {
                 AppendTypeName(sb);
             }
diff --git a/src/Ben.Demystifier/TypeNameHelper.cs b/src/Ben.Demystifier/TypeNameHelper.cs
index a1426ad..bfa1559 100644
--- a/src/Ben.Demystifier/TypeNameHelper.cs
+++ b/src/Ben.Demystifier/TypeNameHelper.cs
@@ -69,8 +69,17 @@ namespace System.Diagnostics
         {
             if (type.IsGenericType)
             {
-                var genericArguments = type.GetGenericArguments();
-                ProcessGenericType(builder, type, genericArguments, genericArguments.Length, options);
+                var underlyingType = Nullable.GetUnderlyingType(type);
+                if (underlyingType != null)
+                {
+                    ProcessType(builder, underlyingType, options);
+                    builder.Append('?');
+                }
+                else
+                {
+                    var genericArguments = type.GetGenericArguments();
+                    ProcessGenericType(builder, type, genericArguments, genericArguments.Length, options);
+                }
             }
             else if (type.IsArray)
             {
diff --git a/test/Ben.Demystifier.Test/MethodTests.cs b/test/Ben.Demystifier.Test/MethodTests.cs
new file mode 100644
index 0000000..c00bb54
--- /dev/null
+++ b/test/Ben.Demystifier.Test/MethodTests.cs
@@ -0,0 +1,65 @@
+namespace Ben.Demystifier.Test
+{
+    using System;
+    using System.Diagnostics;
+    using Xunit;
+
+    public class MethodTests
+    {
+        [Fact]
+        public void DemistifiesMethodWithNullableInt()
+        {
+            Exception dex = null;
+            try
+            {
+                MethodWithNullableInt(1);
+            }
+            catch (Exception e)
+            {
+                dex = e.Demystify();
+            }
+
+            // Assert
+            var stackTrace = dex.ToString();
+            stackTrace = LineEndingsHelper.RemoveLineEndings(stackTrace);
+            var trace = string.Join(string.Empty, stackTrace.Split(new[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries));
+
+            var expected = string.Join(string.Empty, new[] {
+                "System.ArgumentException: Value does not fall within the expected range.",
+                "   at bool Ben.Demystifier.Test.MethodTests.MethodWithNullableInt(int? number)",
+                "   at void Ben.Demystifier.Test.MethodTests.DemistifiesMethodWithNullableInt()"});
+
+            Assert.Equal(expected, trace);
+        }
+        
+        [Fact]
+        public void DemistifiesMethodWithDynamic()
+        {
+            Exception dex = null;
+            try
+            {
+                MethodWithDynamic(1);
+            }
+            catch (Exception e)
+            {
+                dex = e.Demystify();
+            }
+
+            // Assert
+            var stackTrace = dex.ToString();
+            stackTrace = LineEndingsHelper.RemoveLineEndings(stackTrace);
+            var trace = string.Join(string.Empty, stackTrace.Split(new[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries));
+
+            var expected = string.Join(string.Empty, new[] {
+                "System.ArgumentException: Value does not fall within the expected range.",
+                "   at bool Ben.Demystifier.Test.MethodTests.MethodWithDynamic(dynamic value)",
+                "   at void Ben.Demystifier.Test.MethodTests.DemistifiesMethodWithDynamic()"});
+
+            Assert.Equal(expected, trace);
+        }
+
+        private bool MethodWithNullableInt(int? number) => throw new ArgumentException();
+
+        private bool MethodWithDynamic(dynamic value) => throw new ArgumentException();
+    }
+}