[USDU-276] Adds testcase for Force Refreshing USDZ Imported prefab with Import Preview Surface option

package/com.unity.formats.usd/Tests/Editor/BaseFixtureEditor.cs

@@ -13,7 +13,10 @@
 // limitations under the License.
 
 using NUnit.Framework;
+using System.IO;
+using UnityEditor;
 using UnityEditor.SceneManagement;
+using USD.NET;
 
 namespace Unity.Formats.USD.Tests
 {
@@ -24,5 +27,12 @@ public void EnsureEmptyScene()
         {
             m_UnityScene = EditorSceneManager.NewScene(NewSceneSetup.EmptyScene, NewSceneMode.Single);
         }
+
+        protected Scene OpenUSDGUIDAssetScene(string guid, out string filePath)
+        {
+            filePath = Path.GetFullPath(AssetDatabase.GUIDToAssetPath(guid));
+            var stage = pxr.UsdStage.Open(filePath, pxr.UsdStage.InitialLoadSet.LoadNone);
+            return Scene.Open(stage);
+        }
     }
 }

package/com.unity.formats.usd/Tests/Editor/UsdAssetReloadTests.cs

@@ -36,13 +36,6 @@ public void Setup()
             Assume.That(m_usdAsset, Is.Not.Null, "Could not find USDAsset component on root gameobject.");
         }
 
-        private Scene OpenUSDGUIDAssetScene(string guid, out string filePath)
-        {
-            filePath = Path.GetFullPath(AssetDatabase.GUIDToAssetPath(guid));
-            var stage = pxr.UsdStage.Open(filePath, pxr.UsdStage.InitialLoadSet.LoadNone);
-            return Scene.Open(stage);
-        }
-
         [TearDown]
         public void TearDown()
         {

package/com.unity.formats.usd/Tests/Editor/UsdPrefabTests.cs

@@ -0,0 +1,62 @@
+using NUnit.Framework;
+using UnityEditor;
+
+namespace Unity.Formats.USD.Tests
+{
+    public class UsdPrefabTests : BaseFixtureEditor
+    {
+        const string k_USDZGUID = "a90ff3ebef4a2aa42b559da07e4151f5"; // test-roughness.usdz
+
+        static string m_prefabUsdPath;
+
+        [TearDown]
+        public void TearDown()
+        {
+            if (!string.IsNullOrEmpty(m_prefabUsdPath))
+            {
+                AssetDatabase.DeleteAsset(m_prefabUsdPath);
+            }
+        }
+
+        protected void ImportAsPrefab(string usdGUID)
+        {
+            var scene = OpenUSDGUIDAssetScene(usdGUID, out _);
+            m_prefabUsdPath = ImportHelpers.ImportAsPrefab(scene);
+            scene.Close();
+        }
+
+        public class Reload : UsdPrefabTests
+        {
+            [TestCase(MaterialImportMode.ImportDisplayColor)]
+            [TestCase(MaterialImportMode.None)]
+            [TestCase(MaterialImportMode.ImportPreviewSurface)]
+            [Ignore("USDU-276")]
+            public void UsdPrefab_ForceReload_Succeed(MaterialImportMode mode)
+            {
+                ImportAsPrefab(k_USDZGUID);
+
+                var prefabAsset = AssetDatabase.LoadAssetAtPath<UsdAsset>(m_prefabUsdPath);
+                prefabAsset.m_materialImportMode = mode;
+                prefabAsset.Reload(true);
+
+                // Assertion is not required as it will fail on unhandled error
+            }
+
+            [Test]
+            [Ignore("USDU-276")]
+            public void UsdPrefab_ForceReload_ImportPreviewSurface_DoesNotDirtyScene()
+            {
+                var initialRootGameObjects = UnityEngine.SceneManagement.SceneManager.GetActiveScene().GetRootGameObjects();
+                ImportAsPrefab(k_USDZGUID);
+
+                var prefabAsset = AssetDatabase.LoadAssetAtPath<UsdAsset>(m_prefabUsdPath);
+                prefabAsset.m_materialImportMode = MaterialImportMode.ImportPreviewSurface;
+                prefabAsset.Reload(true);
+
+                var newRootGameObjects = UnityEngine.SceneManagement.SceneManager.GetActiveScene().GetRootGameObjects();
+
+                Assert.AreEqual(initialRootGameObjects, newRootGameObjects, "Prefab Reload does not clean up the scene");
+            }
+        }
+    }
+}