Add Empty ViewAliasTests

Author: Kyle-Ye

Sources/OpenSwiftUI/View/ViewAlias.swift

@@ -110,6 +110,7 @@ private protocol AnySourceFormula {
 ///
 /// This is useful for conditionally including views in a hierarchy when their source views
 /// may or may not be defined.
+@propertyWrapper
 struct OptionalViewAlias<Alias>: DynamicProperty where Alias: ViewAlias {
     static func _makeProperty<Value>(in buffer: inout _DynamicPropertyBuffer, container: _GraphValue<Value>, fieldOffset: Int, inputs: inout _GraphInputs) {
         if let source = inputs[SourceInput<Alias>.self].top {
@@ -127,7 +128,7 @@ struct OptionalViewAlias<Alias>: DynamicProperty where Alias: ViewAlias {
     }
 
     /// Indicates whether a source view has been defined for this alias.
-    var sourceExists: Bool
+    var sourceExists: Bool = false
 
     /// Returns an instance of the alias if a source view exists, otherwise `nil`.
     var wrappedValue: Alias? {

Tests/OpenSwiftUITests/View/ViewAliasTests.swift

@@ -0,0 +1,39 @@
+//
+//  ViewAliasTests.swift
+//  OpenSwiftUITests
+
+import Testing
+@testable import OpenSwiftUI
+@_spi(ForOpenSwiftUIOnly)
+import OpenSwiftUICore
+#if os(iOS)
+import UIKit
+#endif
+
+// TODO: Add viewAlias related test after style are implemented
+@MainActor
+struct ViewAliasTests {
+//    struct CustomView: View {
+//        struct Alias: ViewAlias {
+//            init() {}
+//        }
+//    }
+//    @Test
+//    func optionalViewAliasDynamicProperty() {
+//        struct ContentView: View {
+//            @OptionalViewAlias
+//            private var alias: CustomView.Alias?
+//
+//            var body: some View {
+//                CustomView()
+//                    .viewAlias(CustomView.Alias.self) {
+//                        Color.red
+//                    }
+//            }
+//        }
+//        #if os(iOS)
+//        let hostingView = _UIHostingView(rootView: ContentView())
+//        hostingView.render()
+//        #endif
+//    }
+}