Add testing for state properties

Sources/Model/Data Flow/UpdateManager.swift

@@ -27,7 +27,7 @@ public enum UpdateManager {
 
     /// Add a handler that is called when the user interface should update.
     /// - Parameter handler: The handler. The parameter defines whether the whole UI should be force updated.
-    static func addUpdateHandler(handler: @escaping (Bool) -> Void) {
+    public static func addUpdateHandler(handler: @escaping (Bool) -> Void) {
         updateHandlers.append(handler)
     }
 

Tests/DemoApp/DemoApp.swift

@@ -1,19 +1,18 @@
+import Foundation
 import Meta
 import SampleBackends
 
 struct DemoView: View {
 
-    @State private var test = ""
+    @State private var test = "Label"
 
      var view: Body {
-        Wrapper {
-            Backend1.TestWidget1()
-            Backend1.Button(test) {
-                test = "\(Int.random(in: 0...10))"
-            }
-            TestView()
-            testContent
+        Backend1.TestWidget1()
+        Backend1.Button(test) {
+            test = "\(Int.random(in: 1...10))"
         }
+        TestView()
+        testContent
      }
 
      @ViewBuilder
@@ -43,3 +42,10 @@ for round in 0...2 {
     print("#\(round)")
     DemoView().updateStorage(storage, modifiers: modifiers, updateProperties: true, type: backendType)
 }
+
+UpdateManager.addUpdateHandler { _ in
+    print("#Handler")
+    DemoView().updateStorage(storage, modifiers: modifiers, updateProperties: false, type: backendType)
+}
+
+sleep(2)

Tests/SampleBackends/Backend1.swift

@@ -56,7 +56,12 @@ public enum Backend1 {
 
     public struct Button: BackendWidget {
 
+        var label: String
+        var action: () -> Void
+
         public init(_ label: String, action: @escaping () -> Void) {
+            self.label = label
+            self.action = action
         }
 
         public var debugTreeContent: [(String, body: Body)] {
@@ -64,14 +69,24 @@ public enum Backend1 {
         }
 
         public var debugTreeParameters: [(String, value: any CustomStringConvertible)] {
-            []
+            _ = action
+            return [("label", value: label), ("action", value: "() -> Void")]
         }
 
         public func container<WidgetType>(modifiers: [(any AnyView) -> any AnyView], type: WidgetType.Type) -> ViewStorage {
-            .init(nil)
+            Task {
+                try await Task.sleep(for: .seconds(1))
+                action()
+            }
+            return .init(nil)
         }
 
         public func update<WidgetType>(_ storage: ViewStorage, modifiers: [(any AnyView) -> any AnyView], updateProperties: Bool, type: WidgetType.Type) {
+            if updateProperties {
+                print("Update button")
+            } else {
+                print("Do not update button")
+            }
         }
 
     }