Extend CastHelper to utilise explicit conversion methods if they exist (

#2036)
thomhurst · Mar 8, 2025 · 9279c14 · 9279c14
1 parent 19259cc
commit 9279c14
Showing 1 changed file with 24 additions and 9 deletions.
diff --git a/TUnit.Core/Helpers/CastHelper.cs b/TUnit.Core/Helpers/CastHelper.cs
@@ -23,18 +23,33 @@ public static class CastHelper
             return (T?) Enum.ToObject(typeof(T), value);
         }
 
-        return (T?) GetImplicitConversion(value.GetType(), typeof(T)).Invoke(null, [value]);
+        var conversionMethod = GetConversionMethod(value.GetType(), typeof(T));
+
+        if (conversionMethod is null)
+        {
+            return (T?) Convert.ChangeType(value, typeof(T));
+        }
+
+        return (T?) conversionMethod.Invoke(null, [value]);
     }
 
-    private static MethodInfo GetImplicitConversion([DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicMethods)] Type baseType, [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicMethods)] Type targetType)
+    private static MethodInfo? GetConversionMethod([DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicMethods)] Type baseType, [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicMethods)] Type targetType)
     {
-        return baseType.GetMethods(BindingFlags.Public | BindingFlags.Static)
+        var methods = baseType.GetMethods(BindingFlags.Public | BindingFlags.Static)
             .Concat(targetType.GetMethods(BindingFlags.Public | BindingFlags.Static))
-            .Where(mi => mi.Name == "op_Implicit" && mi.ReturnType == targetType)
-            .FirstOrDefault(mi =>
-            {
-                var pi = mi.GetParameters().FirstOrDefault();
-                return pi != null && pi.ParameterType == baseType;
-            }) ?? throw new ArgumentException($"Cannot convert from {baseType} to {targetType}");
+            .ToArray();
+
+        return methods
+                   .FirstOrDefault(mi =>
+                       mi.Name == "op_Implicit" && mi.ReturnType == targetType && HasCorrectInputType(baseType, mi))
+               ?? methods
+                   .FirstOrDefault(mi =>
+                       mi.Name == "op_Explicit" && mi.ReturnType == targetType && HasCorrectInputType(baseType, mi));
+    }
+
+    private static bool HasCorrectInputType(Type baseType, MethodInfo mi)
+    {
+        var pi = mi.GetParameters().FirstOrDefault();
+        return pi != null && pi.ParameterType == baseType;
     }
 }