DisplayList.Value.init(decodedValue:) updates lastValue (#184)

* DisplayList.Value.init(decodedValue:) updates lastValue

* Update test case for DisplayList.Version

---------

Co-authored-by: Kyle <[email protected]>

Author: pookjw

Sources/OpenSwiftUICore/Render/DisplayList/DisplayList.swift

@@ -214,12 +214,16 @@ extension DisplayList {
 //    }
 
     package struct Version: Comparable, Hashable {
+        private static var lastValue: Int = .zero
+        
         package private(set) var value: Int
-
+        
         package init() { value = .zero }
-        package init(decodedValue value: Int) { self.value = value }
 
-        private static var lastValue: Int = .zero
+        package init(decodedValue value: Int) {
+            Version.lastValue = max(Version.lastValue, value)
+            self.value = value
+        }
 
         package init(forUpdate: Void) {
             Version.lastValue &+= 1

Tests/OpenSwiftUICoreTests/Render/DisplayList/DisplayListTests.swift

@@ -0,0 +1,26 @@
+//
+//  DisplayListTests.swift
+//  OpenSwiftUICoreTests
+
+import OpenSwiftUICore
+import Testing
+
+struct DisplayListTests {
+    @Test
+    @MainActor
+    func version() {
+        typealias Version = DisplayList.Version
+        let v0 = Version()
+        let v1 = Version(decodedValue: 999)
+        let v2 = Version(forUpdate: ())
+        #expect(v0.value == 0)
+        #expect(v1.value == 999)
+        #expect(v2.value == 1000)
+        #expect(v1 < v2)
+        
+        var combineVersion = v0
+        #expect(combineVersion.value == 0)
+        combineVersion.combine(with: v1)
+        #expect(combineVersion.value == 999)        
+    }
+}