Add crashing test case

Author: jcmosc

Tests/OpenSwiftUICoreTests/View/VariadicViewTests.swift

@@ -0,0 +1,115 @@
+//
+//  VariadicViewTests.swift
+//  OpenSwiftUICoreTests
+
+import Foundation
+import OpenSwiftUICore
+import Testing
+
+struct PassthroughUnaryViewRoot: _VariadicView.UnaryViewRoot {
+    func body(children: _VariadicView.Children) -> some View {
+        children
+    }
+}
+
+struct PassthroughMultiViewRoot: _VariadicView.MultiViewRoot {
+    func body(children: _VariadicView.Children) -> some View {
+        children
+    }
+}
+
+@MainActor
+struct VariadicViewTests {
+
+    #if canImport(Darwin)
+        @Test
+        func nestedUnaryViewRoot() {
+            struct ContentView: View {
+                var body: some View {
+                    _VariadicView.Tree(PassthroughUnaryViewRoot()) {
+                        _VariadicView.Tree(PassthroughUnaryViewRoot()) {
+                            Color.red
+                            Color.blue
+                        }
+                    }
+                }
+            }
+
+            let graph = ViewGraph(
+                rootViewType: ContentView.self,
+                requestedOutputs: [.displayList]
+            )
+            graph.instantiateOutputs()
+            graph.setRootView(ContentView())
+            graph.setProposedSize(CGSize(width: 100, height: 100))
+            let (displayList, _) = graph.displayList()
+            let expectRegex = try! Regex(
+                #"""
+                \(display-list
+                    \(item #:identity \d+ #:version \d+
+                    \(frame \([^)]+\)\)
+                    \(effect
+                        \(item #:identity \d+ #:version \d+
+                        \(frame \([^)]+\)\)
+                        \(effect
+                            \(item #:identity \d+ #:version \d+
+                            \(frame \([^)]+\)\)
+                            \(content-seed \d+\)
+                            \(color #[0-9A-F]{8}\)\)\)\)
+                        \(item #:identity \d+ #:version \d+
+                        \(frame \([^)]+\)\)
+                        \(effect
+                            \(item #:identity \d+ #:version \d+
+                            \(frame \([^)]+\)\)
+                            \(content-seed \d+\)
+                            \(color #[0-9A-F]{8}\)\)\)\)\)\)\)
+                """#)
+            #expect(displayList.description.contains(expectRegex))
+        }
+
+        @Test
+        func nestedMultiViewRoot() {
+            struct ContentView: View {
+                var body: some View {
+                    _VariadicView.Tree(PassthroughMultiViewRoot()) {
+                        _VariadicView.Tree(PassthroughMultiViewRoot()) {
+                            Color.red
+                            Color.blue
+                        }
+                    }
+                }
+            }
+
+            let graph = ViewGraph(
+                rootViewType: ContentView.self,
+                requestedOutputs: [.displayList]
+            )
+            graph.instantiateOutputs()
+            graph.setRootView(ContentView())
+            graph.setProposedSize(CGSize(width: 100, height: 100))
+            let (displayList, _) = graph.displayList()
+            let expectRegex = try! Regex(
+                #"""
+                \(display-list
+                    \(item #:identity \d+ #:version \d+
+                    \(frame \([^)]+\)\)
+                    \(effect
+                        \(item #:identity \d+ #:version \d+
+                        \(frame \([^)]+\)\)
+                        \(effect
+                            \(item #:identity \d+ #:version \d+
+                            \(frame \([^)]+\)\)
+                            \(content-seed \d+\)
+                            \(color #[0-9A-F]{8}\)\)\)\)
+                        \(item #:identity \d+ #:version \d+
+                        \(frame \([^)]+\)\)
+                        \(effect
+                            \(item #:identity \d+ #:version \d+
+                            \(frame \([^)]+\)\)
+                            \(content-seed \d+\)
+                            \(color #[0-9A-F]{8}\)\)\)\)\)\)\)
+                """#)
+            #expect(displayList.description.contains(expectRegex))
+        }
+    #endif
+}