diff --git a/SampleLibrary/DocFixture.cs b/SampleLibrary/DocFixture.cs
new file mode 100644
index 0000000..6266951
--- /dev/null
+++ b/SampleLibrary/DocFixture.cs
@@ -0,0 +1,25 @@
+using Autodesk.Revit.DB;
+using System;
+using System.Collections.Generic;
+using xUnitRevitUtils;
+
+namespace SampleLibrary {
+    public sealed class DocFixture : IDisposable
+  {
+    public Document Doc { get; set; }
+    public IList<Element> Walls { get; set; }
+
+
+    public DocFixture()
+    {
+      var testModel = Utils.GetTestModel("walls.rvt");
+      Doc = xru.OpenDoc(testModel);
+
+      Walls = new FilteredElementCollector(Doc).WhereElementIsNotElementType().OfCategory(BuiltInCategory.OST_Walls).ToElements();
+    }
+
+    public void Dispose()
+    {
+    }
+  }
+}
diff --git a/SampleLibrary/SampleLibrary.csproj b/SampleLibrary/SampleLibrary.csproj
index 569fd4e..8c4618f 100644
--- a/SampleLibrary/SampleLibrary.csproj
+++ b/SampleLibrary/SampleLibrary.csproj
@@ -66,6 +66,7 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="DocFixture.cs" />
     <Compile Include="SampleTest.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="TestWithFixture.cs" />
diff --git a/SampleLibrary/SampleTest.cs b/SampleLibrary/SampleTest.cs
index 379c68d..6586776 100644
--- a/SampleLibrary/SampleTest.cs
+++ b/SampleLibrary/SampleTest.cs
@@ -68,7 +68,5 @@ namespace SampleLibrary
       }, doc).Wait();
       Assert.True(grossArea > 0);
     }
-
-
   }
 }
diff --git a/SampleLibrary/TestWithFixture.cs b/SampleLibrary/TestWithFixture.cs
index e469a77..56475a6 100644
--- a/SampleLibrary/TestWithFixture.cs
+++ b/SampleLibrary/TestWithFixture.cs
@@ -1,6 +1,4 @@
 using Autodesk.Revit.DB;
-using System;
-using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Text;
@@ -8,27 +6,8 @@ using System.Threading.Tasks;
 using Xunit;
 using xUnitRevitUtils;
 
-namespace SampleLibrary
-{
-  public class DocFixture : IDisposable
-  {
-    public Document Doc { get; set; }
-    public IList<Element> Walls { get; set; }
-
-
-    public DocFixture()
-    {
-      var testModel = Utils.GetTestModel("walls.rvt");
-      Doc = xru.OpenDoc(testModel);
-
-      Walls = new FilteredElementCollector(Doc).WhereElementIsNotElementType().OfCategory(BuiltInCategory.OST_Walls).ToElements();
-    }
-
-    public void Dispose()
-    {
-    }
-  }
-  public class TestWithFixture : IClassFixture<DocFixture>
+namespace SampleLibrary {
+    public class TestWithFixture : IClassFixture<DocFixture>
   {
     DocFixture fixture; 
     public TestWithFixture(DocFixture fixture)
diff --git a/xUnitRevit/App.cs b/xUnitRevit/App.cs
index fd0b8f3..692e827 100644
--- a/xUnitRevit/App.cs
+++ b/xUnitRevit/App.cs
@@ -18,7 +18,6 @@ namespace xUnitRevit
       return Result.Succeeded;
     }
 
-
     private void ControlledApplication_ApplicationInitialized(object sender, Autodesk.Revit.DB.Events.ApplicationInitializedEventArgs e)
     {
       Application app = sender as Application;
@@ -30,7 +29,6 @@ namespace xUnitRevit
         Runner.Launch(uiapp);
     }
 
-
     public Result OnShutdown(UIControlledApplication a)
     {
       return Result.Succeeded;
diff --git a/xUnitRevit/Configuration.cs b/xUnitRevit/Configuration.cs
index 73080e9..293bc42 100644
--- a/xUnitRevit/Configuration.cs
+++ b/xUnitRevit/Configuration.cs
@@ -11,7 +11,7 @@ namespace xUnitRevit
   /// </summary>
   public class Configuration
   {
-    public List<string> startupAssemblies { get; set; } = new List<string>();
+    public IList<string> StartupAssemblies { get; set; } = new List<string>();
     public bool autoStart { get; set; } = false;
   }
 }
diff --git a/xUnitRevit/ExternalEventHandler.cs b/xUnitRevit/ExternalEventHandler.cs
index 07de43d..3d66b69 100644
--- a/xUnitRevit/ExternalEventHandler.cs
+++ b/xUnitRevit/ExternalEventHandler.cs
@@ -16,9 +16,9 @@ namespace xUnitRevit
   {
 
     public bool Running = false;
-    public List<Action> Queue { get; set; }
+    public IList<Action> Queue { get; set; }
 
-    public ExternalEventHandler(List<Action> queue)
+    public ExternalEventHandler(IList<Action> queue)
     {
       Queue = queue;
     }
diff --git a/xUnitRevit/Runner.cs b/xUnitRevit/Runner.cs
index f3e2926..6b8b969 100644
--- a/xUnitRevit/Runner.cs
+++ b/xUnitRevit/Runner.cs
@@ -34,13 +34,11 @@ namespace xUnitRevit
         main.MaxHeight = 800;
 
         //pre-load asssemblies, if you're a lazy developer
-        (main.DataContext as MainViewModel).StartupAssemblies = Config.startupAssemblies;
+        if (main.DataContext is MainViewModel mainViewModel)
+            mainViewModel.StartupAssemblies = Config.StartupAssemblies.ToList();
         main.Show();
-
-
       }
-      catch (Exception e)
-      {
+      catch (Exception) {
         //fail silently
       }
     }
@@ -59,5 +57,4 @@ namespace xUnitRevit
       {}
     }
   }
-
 }
diff --git a/xUnitRevitUtils2021/xru.cs b/xUnitRevitUtils2021/xru.cs
index 00895b4..037d209 100644
--- a/xUnitRevitUtils2021/xru.cs
+++ b/xUnitRevitUtils2021/xru.cs
@@ -18,12 +18,12 @@ namespace xUnitRevitUtils
   {
     public static UIApplication Uiapp { get; set; }
 
-    private static List<Action> Queue { get; set; }
+    private static IList<Action> Queue { get; set; }
     private static ExternalEvent EventHandler { get; set; }
 
     public static SynchronizationContext UiContext { get; set; }
 
-    public static void Initialize(UIApplication uiapp, SynchronizationContext uiContext, ExternalEvent eventHandler, List<Action> queue)
+    public static void Initialize(UIApplication uiapp, SynchronizationContext uiContext, ExternalEvent eventHandler, IList<Action> queue)
     {
       Uiapp = uiapp;
       UiContext = uiContext;
@@ -33,12 +33,11 @@ namespace xUnitRevitUtils
 
     #region utility methods
 
-
     /// <summary>
     /// Returns the selected elements in the active document
     /// </summary>
     /// <returns></returns>
-    public static List<Element> GetActiveSelection()
+    public static IList<Element> GetActiveSelection()
     {
       Assert.NotNull(Uiapp);
 
@@ -60,7 +59,6 @@ namespace xUnitRevitUtils
       return doc;
     }
 
-
     /// <summary>
     /// Creates a new empty document
     /// </summary>
@@ -98,7 +96,6 @@ namespace xUnitRevitUtils
       return doc;
     }
 
-
     /// <summary>
     /// Runs an Action in a Revit transaction, uses TaskCompletionSource to communicate when done
     /// </summary>
@@ -139,7 +136,6 @@ namespace xUnitRevitUtils
       EventHandler.Raise();
 
       return tcs.Task;
-
     }
 
     /// <summary>
@@ -167,7 +163,6 @@ namespace xUnitRevitUtils
       EventHandler.Raise();
 
       return tcs.Task;
-
     }
 
     /// <summary>
@@ -188,7 +183,6 @@ namespace xUnitRevitUtils
       }
     }
 
-
     #endregion
   }
 }
diff --git a/xUnitRevitUtils2022/xru.cs b/xUnitRevitUtils2022/xru.cs
index e24fb25..c84a2b2 100644
--- a/xUnitRevitUtils2022/xru.cs
+++ b/xUnitRevitUtils2022/xru.cs
@@ -17,10 +17,10 @@ namespace xUnitRevitUtils
   public static class xru
   {
     public static UIApplication Uiapp { get; set; }
-    private static List<Action> Queue { get; set; }
+    private static IList<Action> Queue { get; set; }
     private static ExternalEvent EventHandler { get; set; }
     public static SynchronizationContext UiContext { get; set; }
-    public static void Initialize(UIApplication uiapp, SynchronizationContext uiContext, ExternalEvent eventHandler, List<Action> queue)
+    public static void Initialize(UIApplication uiapp, SynchronizationContext uiContext, ExternalEvent eventHandler, IList<Action> queue)
     {
       Uiapp = uiapp;
       UiContext = uiContext;
@@ -30,12 +30,11 @@ namespace xUnitRevitUtils
 
     #region utility methods
 
-
     /// <summary>
     /// Returns the selected elements in the active document
     /// </summary>
     /// <returns></returns>
-    public static List<Element> GetActiveSelection()
+    public static IList<Element> GetActiveSelection()
     {
       Assert.NotNull(Uiapp);
 
@@ -57,7 +56,6 @@ namespace xUnitRevitUtils
       return doc;
     }
 
-
     /// <summary>
     /// Creates a new empty document
     /// </summary>
@@ -95,7 +93,6 @@ namespace xUnitRevitUtils
       return doc;
     }
 
-
     /// <summary>
     /// Runs an Action in a Revit transaction, uses TaskCompletionSource to communicate when done
     /// </summary>
@@ -136,7 +133,6 @@ namespace xUnitRevitUtils
       EventHandler.Raise();
 
       return tcs.Task;
-
     }
 
     /// <summary>
@@ -164,7 +160,6 @@ namespace xUnitRevitUtils
       EventHandler.Raise();
 
       return tcs.Task;
-
     }
 
     /// <summary>
@@ -184,8 +179,6 @@ namespace xUnitRevitUtils
         return FailureProcessingResult.Continue;
       }
     }
-
-
     #endregion
   }
 }
diff --git a/xUnitRevitUtils2023/xru.cs b/xUnitRevitUtils2023/xru.cs
index e24fb25..c84a2b2 100644
--- a/xUnitRevitUtils2023/xru.cs
+++ b/xUnitRevitUtils2023/xru.cs
@@ -17,10 +17,10 @@ namespace xUnitRevitUtils
   public static class xru
   {
     public static UIApplication Uiapp { get; set; }
-    private static List<Action> Queue { get; set; }
+    private static IList<Action> Queue { get; set; }
     private static ExternalEvent EventHandler { get; set; }
     public static SynchronizationContext UiContext { get; set; }
-    public static void Initialize(UIApplication uiapp, SynchronizationContext uiContext, ExternalEvent eventHandler, List<Action> queue)
+    public static void Initialize(UIApplication uiapp, SynchronizationContext uiContext, ExternalEvent eventHandler, IList<Action> queue)
     {
       Uiapp = uiapp;
       UiContext = uiContext;
@@ -30,12 +30,11 @@ namespace xUnitRevitUtils
 
     #region utility methods
 
-
     /// <summary>
     /// Returns the selected elements in the active document
     /// </summary>
     /// <returns></returns>
-    public static List<Element> GetActiveSelection()
+    public static IList<Element> GetActiveSelection()
     {
       Assert.NotNull(Uiapp);
 
@@ -57,7 +56,6 @@ namespace xUnitRevitUtils
       return doc;
     }
 
-
     /// <summary>
     /// Creates a new empty document
     /// </summary>
@@ -95,7 +93,6 @@ namespace xUnitRevitUtils
       return doc;
     }
 
-
     /// <summary>
     /// Runs an Action in a Revit transaction, uses TaskCompletionSource to communicate when done
     /// </summary>
@@ -136,7 +133,6 @@ namespace xUnitRevitUtils
       EventHandler.Raise();
 
       return tcs.Task;
-
     }
 
     /// <summary>
@@ -164,7 +160,6 @@ namespace xUnitRevitUtils
       EventHandler.Raise();
 
       return tcs.Task;
-
     }
 
     /// <summary>
@@ -184,8 +179,6 @@ namespace xUnitRevitUtils
         return FailureProcessingResult.Continue;
       }
     }
-
-
     #endregion
   }
 }