fix: crash bugs, add UE automation tests, update docs and metadata

- Fix 3 crash bugs in AssetConstructor.cpp: remove check() assertions on
  failure path and add early return nullptr after setting Failure result in
  ConstructProceduralMesh/StaticMesh/DynamicMeshComponentFromAssetFile
- Fix potential crash in AssetLoader.cpp: add IsEmpty() guard before
  accessing &AssetData[0] in LoadAiScene to prevent undefined behavior
- Add RuntimeAssetImportTest module with UE Automation Tests covering:
  LoadMeshFromAssetFile with non-existent path, empty path, and
  LoadMeshFromAssetData with empty array (all should return Failure not crash)
- Pin assimp submodule to latest stable release tag
- Update RuntimeAssetImport.uplugin: improve description, set Category to
  Mesh, add RuntimeAssetImportTest module entry
- Update README.md: fix trailing backtick typo in git clone command, add
  known bugs section (multiplayer ProceduralMesh, packaged StaticMesh),
  add assimp first-build time note, clarify macOS arm64-only support,
  add Content folder asset descriptions, add Running Tests section

Author: metyatech

README.md

@@ -3,10 +3,12 @@
 This is a plugin for the Unreal Engine to load 3D assets (e.g. FBX) at runtime. Made with UE5.4.2.
 
 ## Prerequisites
-- Windows is the primary supported platform. macOS and Linux support is experimental (build scripts are present but not officially tested).
+- Windows is the primary supported platform. macOS (arm64 only; x86_64 not supported) and Linux support is experimental.
 - Download and install [CMake](https://cmake.org/)
   The check box "Add CMake to the PATH environment variable" that appears during installation must be checked.
 
+> **Note:** The first build of the assimp library (a C++ dependency) takes approximately 5 or more minutes. Subsequent builds are fast. This is expected behavior.
+
 ## How to install
 Clone this repository with its submodules into the Plugins folder (or create your own if you don't have one) in the folder of the Unreal Engine project where you want to install this plugin by doing one of the following:
 <details>
@@ -25,7 +27,7 @@ Clone this repository with its submodules into the Plugins folder (or create you
 2. In the Plugins folder of the project where you want to install this plug-in, start a command prompt.
 3. Execute  
    ```
-   git clone --recursive URL`
+   git clone --recursive URL
    ```
    Put the URL of this repository in the URL field.
 </details>
@@ -43,6 +45,30 @@ The following file formats are supported via assimp:
 - DAE (Collada)
 - Other formats supported by assimp
 
+## Content Folder Assets
+
+The plugin's `Content` folder includes the following assets:
+
+- **`AssetImporterMeshMaterial.uasset`** — Parent material used by the plugin. Exposes the following parameters:
+  - `TextureBlendIntensityForBaseColor` — blend intensity between texture and base color
+  - `BaseColor4` — base color as a 4-component vector
+  - `BaseColorTexture` — texture input for base color
+- **`purple.uasset`** — Sample purple texture for testing and demonstration purposes.
+
+## Known Bugs
+
+- **Multiplayer (ProceduralMesh):** Clients may experience abnormal movement accompanied by a `LogNetPackageMap` warning. Use `DynamicMeshComponent` instead as a workaround.
+- **Packaged game materials (StaticMesh):** Materials display as a checkerboard pattern in packaged builds. Use `DynamicMeshComponent` instead as a workaround.
+
+## Running Tests
+
+To run from the command line:
+```
+UnrealEditor.exe <YourProject>.uproject -ExecCmds="Automation RunTests RuntimeAssetImport" -unattended -nopause -log -testexit="Automation Test Queue Empty"
+```
+
+Or from the UE Editor UI: **Window > Test Automation**, search `RuntimeAssetImport`, click **Start Tests**.
+
 ## Known Limitations
 - Only embedded textures are loaded (external texture file references are not yet supported)
 - Only 1 texture per material is supported

RuntimeAssetImport.uplugin

@@ -3,8 +3,8 @@
 	"Version": 1,
 	"VersionName": "1.0",
 	"FriendlyName": "RuntimeAssetImport",
-	"Description": "Plugin to load mesh at runtime.",
-	"Category": "Other",
+	"Description": "Runtime mesh loading plugin for Unreal Engine 5. Supports FBX, glTF/GLB, OBJ, DAE and other formats via the Assimp library.",
+	"Category": "Mesh",
 	"EngineVersion": "5.4.0",
 	"CreatedBy": "Udon-Tobira",
 	"CreatedByURL": "https://github.com/metyatech",
@@ -29,6 +29,11 @@
 			"Name": "RuntimeAssetImport",
 			"Type": "Runtime",
 			"LoadingPhase": "PreDefault"
+		},
+		{
+			"Name": "RuntimeAssetImportTest",
+			"Type": "Developer",
+			"LoadingPhase": "Default"
 		}
 	],
 	"Plugins": [

Source/RuntimeAssetImport/Private/AssetConstructor.cpp

@@ -100,8 +100,8 @@ UProceduralMeshComponent*
 	if (ELoadMeshFromAssetFileResult::Failure == LoadMeshFromAssetFileResult) {
 		ConstructProceduralMeshComponentFromAssetFileResult =
 		    EConstructProceduralMeshComponentFromAssetFileResult::Failure;
+		return nullptr;
 	}
-	check(ELoadMeshFromAssetFileResult::Success == LoadMeshFromAssetFileResult);
 
 	// assume the result is success
 	ConstructProceduralMeshComponentFromAssetFileResult =
@@ -135,8 +135,8 @@ UStaticMeshComponent*
 	if (ELoadMeshFromAssetFileResult::Failure == LoadMeshFromAssetFileResult) {
 		ConstructStaticMeshComponentFromAssetFileResult =
 		    EConstructStaticMeshComponentFromAssetFileResult::Failure;
+		return nullptr;
 	}
-	check(ELoadMeshFromAssetFileResult::Success == LoadMeshFromAssetFileResult);
 
 	// assume the result is success
 	ConstructStaticMeshComponentFromAssetFileResult =
@@ -170,8 +170,8 @@ UDynamicMeshComponent*
 	if (ELoadMeshFromAssetFileResult::Failure == LoadMeshFromAssetFileResult) {
 		ConstructDynamicMeshComponentFromAssetFileResult =
 		    EConstructDynamicMeshComponentFromAssetFileResult::Failure;
+		return nullptr;
 	}
-	check(ELoadMeshFromAssetFileResult::Success == LoadMeshFromAssetFileResult);
 
 	// assume the result is success
 	ConstructDynamicMeshComponentFromAssetFileResult =

Source/RuntimeAssetImport/Private/AssetLoader.cpp

@@ -156,6 +156,9 @@ static const aiScene* LoadAiScene(Assimp::Importer& AiImporter,
 
 static const aiScene* LoadAiScene(Assimp::Importer&    AiImporter,
                                   const TArray<uint8>& AssetData) {
+	if (AssetData.IsEmpty()) {
+		return nullptr;
+	}
 	// import
 	return AiImporter.ReadFileFromMemory(&AssetData[0], AssetData.Num(),
 	                                     AiImportFlags);

Source/RuntimeAssetImportTest/Private/AssetLoaderTest.cpp

@@ -0,0 +1,53 @@
+#include "AssetLoader.h"
+#include "CoreMinimal.h"
+#include "Misc/AutomationTest.h"
+
+IMPLEMENT_SIMPLE_AUTOMATION_TEST(
+    FLoadMeshFromAssetFile_NonExistentPath_ReturnsFailure,
+    "RuntimeAssetImport.AssetLoader.LoadMeshFromAssetFile.NonExistentPath",
+    EAutomationTestFlags::ApplicationContextMask | EAutomationTestFlags::ProductFilter)
+
+bool FLoadMeshFromAssetFile_NonExistentPath_ReturnsFailure::RunTest(const FString& Parameters)
+{
+    ELoadMeshFromAssetFileResult Result;
+    FLoadedMeshData MeshData = UAssetLoader::LoadMeshFromAssetFile(
+        TEXT("C:/nonexistent/path/does_not_exist.fbx"), Result);
+
+    TestEqual(
+        TEXT("Loading a non-existent file should return Failure without crashing"),
+        Result, ELoadMeshFromAssetFileResult::Failure);
+    return true;
+}
+
+IMPLEMENT_SIMPLE_AUTOMATION_TEST(
+    FLoadMeshFromAssetFile_EmptyPath_ReturnsFailure,
+    "RuntimeAssetImport.AssetLoader.LoadMeshFromAssetFile.EmptyPath",
+    EAutomationTestFlags::ApplicationContextMask | EAutomationTestFlags::ProductFilter)
+
+bool FLoadMeshFromAssetFile_EmptyPath_ReturnsFailure::RunTest(const FString& Parameters)
+{
+    ELoadMeshFromAssetFileResult Result;
+    FLoadedMeshData MeshData = UAssetLoader::LoadMeshFromAssetFile(TEXT(""), Result);
+
+    TestEqual(
+        TEXT("Loading with an empty path should return Failure without crashing"),
+        Result, ELoadMeshFromAssetFileResult::Failure);
+    return true;
+}
+
+IMPLEMENT_SIMPLE_AUTOMATION_TEST(
+    FLoadMeshFromAssetData_EmptyArray_ReturnsFailure,
+    "RuntimeAssetImport.AssetLoader.LoadMeshFromAssetData.EmptyArray",
+    EAutomationTestFlags::ApplicationContextMask | EAutomationTestFlags::ProductFilter)
+
+bool FLoadMeshFromAssetData_EmptyArray_ReturnsFailure::RunTest(const FString& Parameters)
+{
+    ELoadMeshFromAssetDataResult Result;
+    TArray<uint8> EmptyData;
+    FLoadedMeshData MeshData = UAssetLoader::LoadMeshFromAssetData(EmptyData, Result);
+
+    TestEqual(
+        TEXT("Loading from an empty byte array should return Failure without crashing"),
+        Result, ELoadMeshFromAssetDataResult::Failure);
+    return true;
+}

Source/RuntimeAssetImportTest/Private/RuntimeAssetImportTest.cpp

@@ -0,0 +1,3 @@
+#include "Modules/ModuleManager.h"
+
+IMPLEMENT_MODULE(FDefaultModuleImpl, RuntimeAssetImportTest)

Source/RuntimeAssetImportTest/RuntimeAssetImportTest.Build.cs

@@ -0,0 +1,12 @@
+using UnrealBuildTool;
+
+public class RuntimeAssetImportTest : ModuleRules
+{
+    public RuntimeAssetImportTest(ReadOnlyTargetRules Target) : base(Target)
+    {
+        PCHUsage = ModuleRules.PCHUsageMode.UseExplicitOrSharedPCHs;
+
+        PublicDependencyModuleNames.AddRange(new string[] { "Core", "RuntimeAssetImport" });
+        PrivateDependencyModuleNames.AddRange(new string[] { "CoreUObject", "Engine" });
+    }
+}