Enhance data source handling to support class-level ArgumentsAttribut…

TUnit.Core.SourceGenerator/CodeGenerationHelpers.cs

@@ -1,3 +1,4 @@
+using System.Collections.Immutable;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using TUnit.Core.SourceGenerator.CodeGenerators.Helpers;
@@ -55,7 +56,7 @@ public static string GenerateParameterMetadataArray(IMethodSymbol method)
     /// <summary>
     /// Generates direct instantiation code for attributes.
     /// </summary>
-    public static string GenerateAttributeInstantiation(AttributeData attr, IMethodSymbol? targetMethod = null)
+    public static string GenerateAttributeInstantiation(AttributeData attr, ImmutableArray<IParameterSymbol> targetParameters = default)
     {
         var typeName = attr.AttributeClass!.GloballyQualified();
         using var writer = new CodeWriter("", includeHeader: false);
@@ -75,9 +76,9 @@ public static string GenerateAttributeInstantiation(AttributeData attr, IMethodS
 
             // Determine if this is an Arguments attribute and get parameter types
             ITypeSymbol[]? parameterTypes = null;
-            if (attr.AttributeClass?.Name == "ArgumentsAttribute" && targetMethod != null)
+            if (attr.AttributeClass?.Name == "ArgumentsAttribute" && !targetParameters.IsDefault)
             {
-                parameterTypes = targetMethod.Parameters.Select(p => p.Type).ToArray();
+                parameterTypes = targetParameters.Select(p => p.Type).ToArray();
             }
 
             var syntaxIndex = 0;

TUnit.Core.SourceGenerator/Generators/TestMetadataGenerator.cs

@@ -653,7 +653,7 @@
 
             foreach (var attr in methodDataSources)
             {
-                GenerateDataSourceAttribute(writer, attr, methodSymbol, typeSymbol);
+                GenerateDataSourceAttribute(writer, attr, methodSymbol, typeSymbol, isClassDataSource: false);
             }
 
             writer.Unindent();
@@ -673,7 +673,7 @@
 
             foreach (var attr in classDataSources)
             {
-                GenerateDataSourceAttribute(writer, attr, methodSymbol, typeSymbol);
+                GenerateDataSourceAttribute(writer, attr, methodSymbol, typeSymbol, isClassDataSource: true);
             }
 
             writer.Unindent();
@@ -684,7 +684,7 @@
         GeneratePropertyDataSources(writer, compilation, testMethod);
     }
 
-    private static void GenerateDataSourceAttribute(CodeWriter writer, AttributeData attr, IMethodSymbol methodSymbol, INamedTypeSymbol typeSymbol)
+    private static void GenerateDataSourceAttribute(CodeWriter writer, AttributeData attr, IMethodSymbol methodSymbol, INamedTypeSymbol typeSymbol, bool isClassDataSource = false)
     {
         var attrClass = attr.AttributeClass;
         if (attrClass == null)
@@ -702,8 +702,31 @@
         {
             // Use the generic attribute instantiation method for all other attributes
             // This properly handles generics on the attribute type
-            // Pass methodSymbol for ArgumentsAttribute to preserve decimal precision
-            var generatedCode = CodeGenerationHelpers.GenerateAttributeInstantiation(attr, methodSymbol);
+            // For class-level ArgumentsAttribute, pass constructor parameters
+            // For method-level ArgumentsAttribute, pass method parameters
+            ImmutableArray<IParameterSymbol> parameters = default;
+            if (attr.AttributeClass?.Name == "ArgumentsAttribute")
+            {
+                if (isClassDataSource)
+                {
+                    // Get the constructor parameters for class-level Arguments
+                    var constructor = typeSymbol.Constructors
+                        .Where(c => !c.IsStatic && c.DeclaredAccessibility == Accessibility.Public)
+                        .OrderByDescending(c => c.Parameters.Length)
+                        .FirstOrDefault();
+                    if (constructor != null)
+                    {
+                        parameters = constructor.Parameters;
+                    }
+                }
+                else
+                {
+                    // Use method parameters for method-level Arguments
+                    parameters = methodSymbol.Parameters;
+                }
+            }
+
+            var generatedCode = CodeGenerationHelpers.GenerateAttributeInstantiation(attr, parameters);
             writer.AppendLine($"{generatedCode},");
         }
     }
@@ -743,7 +766,7 @@
         }
 
         // Find the data source method
         var dataSourceMethod = targetType.GetMembers(methodName)
             .OfType<IMethodSymbol>()
             .FirstOrDefault();
 
@@ -1278,7 +1301,7 @@
                             writer.AppendLine($"PropertyName = \"{property.Name}\",");
                             writer.AppendLine($"PropertyType = typeof({property.Type.GloballyQualified()}),");
                             writer.Append("DataSource = ");
-                            GenerateDataSourceAttribute(writer, dataSourceAttr, testMethod.MethodSymbol, typeSymbol);
+                            GenerateDataSourceAttribute(writer, dataSourceAttr, testMethod.MethodSymbol, typeSymbol, isClassDataSource: false);
                             writer.Unindent();
                             writer.AppendLine("},");
                         }
@@ -4262,7 +4285,7 @@
 
             foreach (var attr in methodDataSources)
             {
-                GenerateDataSourceAttribute(writer, attr, methodSymbol, typeSymbol);
+                GenerateDataSourceAttribute(writer, attr, methodSymbol, typeSymbol, isClassDataSource: false);
             }
 
             writer.Unindent();
@@ -4282,7 +4305,7 @@
 
             foreach (var attr in classDataSources)
             {
-                GenerateDataSourceAttribute(writer, attr, methodSymbol, typeSymbol);
+                GenerateDataSourceAttribute(writer, attr, methodSymbol, typeSymbol, isClassDataSource: true);
             }
 
             writer.Unindent();
@@ -4546,7 +4569,7 @@
             writer.AppendLine("DataSources = new global::TUnit.Core.IDataSourceAttribute[]");
             writer.AppendLine("{");
             writer.Indent();
-            GenerateDataSourceAttribute(writer, methodDataSourceAttribute, testMethod.MethodSymbol, testMethod.TypeSymbol);
+            GenerateDataSourceAttribute(writer, methodDataSourceAttribute, testMethod.MethodSymbol, testMethod.TypeSymbol, isClassDataSource: false);
             writer.Unindent();
             writer.AppendLine("},");
         }
@@ -4561,7 +4584,7 @@
             writer.AppendLine("ClassDataSources = new global::TUnit.Core.IDataSourceAttribute[]");
             writer.AppendLine("{");
             writer.Indent();
-            GenerateDataSourceAttribute(writer, classDataSourceAttribute, testMethod.MethodSymbol, testMethod.TypeSymbol);
+            GenerateDataSourceAttribute(writer, classDataSourceAttribute, testMethod.MethodSymbol, testMethod.TypeSymbol, isClassDataSource: true);
             writer.Unindent();
             writer.AppendLine("},");
         }

TUnit.TestProject/ClassWithStringConstructorArgumentsTest.cs

@@ -0,0 +1,16 @@
+using TUnit.TestProject.Attributes;
+
+namespace TUnit.TestProject;
+
+[EngineTest(ExpectedResult.Pass)]
+[Arguments("Hello")]
+[Arguments("World")]
+public class ClassWithStringConstructorArgumentsTest(string title)
+{
+    [Test]
+    public async Task TestWithStringConstructorArgument()
+    {
+        await Assert.That(title).IsNotNull();
+        await Assert.That(title).IsIn("Hello", "World");
+    }
+}