System.AccessViolationException when creating a new Node2D in a unit test with xUnit

[DevSavvySerge]

Tested versions

• Reproductible in Godot 4.2.1 & 4.2.2

System information

Windows 10 - Godot 4.2.2

Issue description

System.AccessViolationException when creating a new Node2D in a unit test with xUnit

Description

When running a simple unit test using xUnit that creates a new instance of Node2D, the test host process crashes with a System.AccessViolationException. This issue occurs consistently and seems to indicate memory corruption.

Reproducibility

100% - The error occurs every time the test is run.

Additional Information

• the issue occurs with other nodes (not just Node2D).

Steps to reproduce

Steps to Reproduce

1. Create a new project in Godot.

2. Add a C# script file named UnitTest1.cs with the following code:

   using Godot;
   using Xunit;
   
   namespace Test2
   {
       public class UnitTest1
       {
           [Fact]
           public void Test1()
           {
               var o = new Node2D();
           }
       }
   }

3. Run the unit test using the dotnet test command.

Expected Result

The test should pass without any exceptions.

Actual Result

The test host process crashes with the following error:

The active test run was aborted. Reason: Test host process crashed : Fatal error. System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
   at Godot.NativeInterop.NativeFuncs.godotsharp_string_new_with_utf16_chars(Godot.NativeInterop.godot_string ByRef, Char*)
   at Godot.NativeInterop.Marshaling.ConvertStringToNative(System.String)
   at Godot.NativeInterop.NativeFuncs.godotsharp_string_name_new_from_string(System.String)
   at Godot.StringName..ctor(System.String)
   at Godot.StringName.op_Implicit(System.String)
   at Godot.Node2D..cctor()
   at Godot.Node2D..ctor()
   at Test2.UnitTest1.Test1()
   ...

Minimal reproduction project (MRP)

N/A

<Project Sdk="Microsoft.NET.Sdk">

 <PropertyGroup>
   <TargetFramework>net8.0</TargetFramework>
   <ImplicitUsings>enable</ImplicitUsings>
   <Nullable>enable</Nullable>

   <IsPackable>false</IsPackable>
   <IsTestProject>true</IsTestProject>
 </PropertyGroup>

 <ItemGroup>
   <PackageReference Include="coverlet.collector" Version="6.0.0" />
   <PackageReference Include="GodotSharp" Version="4.2.2" />
   <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
   <PackageReference Include="xunit" Version="2.5.3" />
   <PackageReference Include="xunit.runner.visualstudio" Version="2.5.3" />
 </ItemGroup>

 <ItemGroup>
   <Using Include="Xunit" />
 </ItemGroup>

</Project>

[AThousandShips]

Is xUnit officially supported in any way? This doesn't seem like a Godot issue necessarily

[DevSavvySerge]

Be it xUnit or any other framework (but Godot?), the issue actually is you cannot create Node2d based objects which makes it impossible for running some tests automatically.

[AThousandShips]

Are you running the code from within Godot? Or as a separate application?

[DevSavvySerge]

As a separate application. To my current knowledge, the only way to run code from within Godot is to actually run a scene.

[AThousandShips]

It is not possible to run Godot code as an isolated application, see godotengine/godot#92906 (comment)

This might be something to document

[DevSavvySerge]

Would the only solution be to create a scene and trigger tests from within? Meaning creating some kind of tests runner running within godot?

[AThousandShips]

Indeed, the C# bindings are just bindings, all the background code is run in c++ within the engine, with a few exceptions all the classes in C# are just calling engine methods to do the work, there's no version of the engine written in C# directly

[DevSavvySerge]

Ok, thank you for the quick answer. That is important knowledge to start with.

[AThousandShips]

Let's see if the dotnet team thinks this should be documented more clearly, but moving this to the documentation repo as it's a documentation issue and not part of the class reference

[reuben-ahmed]

@DevSavvySerge , do you have a simple example of executing that C# code in a unit test? We're having the same issue here, I understand the problem, but I don't know how to fix it yet lol.