refactor: replace Dictionary with ConcurrentDictionary for thread-saf…

…e property injection

TUnit.Core/TestDetails.cs

@@ -1,3 +1,4 @@
+using System.Collections.Concurrent;
 using System.Diagnostics.CodeAnalysis;
 using TUnit.Core.Interfaces;
 
@@ -32,10 +33,8 @@ public partial class TestDetails : ITestIdentity, ITestClass, ITestMethod, ITest
     public string TestFilePath { get; set; } = "";
     public int TestLineNumber { get; set; }
     public required Type ReturnType { get; set; }
-    public IDictionary<string, object?> TestClassInjectedPropertyArguments { get; init; } = new Dictionary<string, object?>();
-    public List<string> Categories { get; } =
-    [
-    ];
+    public IDictionary<string, object?> TestClassInjectedPropertyArguments { get; init; } = new ConcurrentDictionary<string, object?>();
+    public List<string> Categories { get; } = [];
     public Dictionary<string, List<string>> CustomProperties { get; } = new();
     public Type[]? TestClassParameterTypes { get; set; }
 

TUnit.Engine/Services/PropertyInitializationOrchestrator.cs

@@ -124,10 +124,11 @@ private async Task InitializeSourceGeneratedPropertyAsync(
         // Set the property value
         metadata.SetProperty(instance, resolvedValue);
 
-        // Store for potential reuse
-        if (testContext != null && !testContext.Metadata.TestDetails.TestClassInjectedPropertyArguments.ContainsKey(metadata.PropertyName))
+        // Store for potential reuse (using TryAdd for thread-safe concurrent access)
+        if (testContext != null)
         {
-            testContext.Metadata.TestDetails.TestClassInjectedPropertyArguments[metadata.PropertyName] = resolvedValue;
+            ((ConcurrentDictionary<string, object?>)testContext.Metadata.TestDetails.TestClassInjectedPropertyArguments)
+                .TryAdd(metadata.PropertyName, resolvedValue);
         }
     }