diff --git a/Sources/CollectionView/CellFactory.swift b/Sources/CollectionView/CellFactory.swift
index a828584d4530531310ddb99969c7aeffda88a983..bc7bc9bec131565d07dc5805865bdcc13e0959dc 100644
--- a/Sources/CollectionView/CellFactory.swift
+++ b/Sources/CollectionView/CellFactory.swift
@@ -1,4 +1,5 @@
 import UIKit
+import XCTestDynamicOverlay
 
 public struct CellFactory<Model> {
   public struct Registrar {
@@ -65,10 +66,10 @@ extension CellFactory {
 
 #if DEBUG
 extension CellFactory {
-  public static func failing() -> CellFactory {
+  public static func unimplemented() -> CellFactory {
     CellFactory(
-      register: .init { _ in fatalError("Not implemented") },
-      build: .init { _, _, _ in fatalError("Not implemented") }
+      register: .init(register: XCTUnimplemented("\(Self.self).Registrar")),
+      build: .init(build: XCTUnimplemented("\(Self.self).Builder"))
     )
   }
 }
diff --git a/Sources/CollectionView/ViewConfigurator.swift b/Sources/CollectionView/ViewConfigurator.swift
index 67e0453b3e44ab5806cc2d71b67aa405afc0321b..eb3e744cbeb7ec4096b9fe984c89638fc05b434b 100644
--- a/Sources/CollectionView/ViewConfigurator.swift
+++ b/Sources/CollectionView/ViewConfigurator.swift
@@ -1,4 +1,5 @@
 import UIKit
+import XCTestDynamicOverlay
 
 public struct ViewConfigurator<View: UIView, Model> {
   public init(configure: @escaping (View, Model) -> Void) {
@@ -14,8 +15,8 @@ public struct ViewConfigurator<View: UIView, Model> {
 
 #if DEBUG
 extension ViewConfigurator {
-  public static func failing() -> ViewConfigurator {
-    ViewConfigurator { _, _ in fatalError("Not implemented") }
+  public static func unimplemented() -> ViewConfigurator {
+    ViewConfigurator(configure: XCTUnimplemented("\(Self.self)"))
   }
 }
 #endif