Add ForwardListTests

Author: Kyle-Ye

Package.swift

@@ -176,6 +176,7 @@ let openAttributeGraphCxxTestsTarget = Target.testTarget(
         "OpenAttributeGraphCxx",
     ],
     exclude: ["README.md"],
+    cSettings: sharedCSettings + [.define("SWIFT_TESTING")],
     swiftSettings: sharedSwiftSettings + [.interoperabilityMode(.Cxx)]
 )
 let openAttributeGraphShimsTestsTarget = Target.testTarget(

Tests/OpenAttributeGraphCxxTests/Util/ForwardListTests.swift

@@ -0,0 +1,61 @@
+//
+//  ForwardListTests.swift
+//  OpenAttributeGraphCxxTests
+
+import OpenAttributeGraphCxx_Private.Util
+import Testing
+
+struct ForwardListTests {
+    @Test
+    func forwardListBasicOperations() {
+        let list = util.UInt64ForwardList.create()
+        defer { util.UInt64ForwardList.destroy(list) }
+        
+        // Test empty list
+        #expect(list.empty())
+        
+        // Test push_front and empty state
+        list.push_front(42)
+        #expect(!list.empty())
+        
+        // Test front access
+        #expect(list.front() == 42)
+        
+        // Test multiple push_front operations
+        list.push_front(100)
+        #expect(list.front() == 100)
+        
+        list.push_front(200)
+        #expect(list.front() == 200)
+        
+        // Test pop_front
+        list.pop_front()
+        #expect(list.front() == 100)
+        
+        list.pop_front()
+        #expect(list.front() == 42)
+        
+        list.pop_front()
+        #expect(list.empty())
+    }
+    
+    @Test
+    func forwardListSequentialOperations() {
+        let list = util.UInt64ForwardList.create()
+        defer { util.UInt64ForwardList.destroy(list) }
+        
+        // Add multiple elements
+        for i in 0..<5 {
+            list.push_front(UInt64(i))
+        }
+        
+        // Remove all elements and verify order (LIFO - last in, first out)
+        for i in (0..<5).reversed() {
+            #expect(!list.empty())
+            #expect(list.front() == UInt64(i))
+            list.pop_front()
+        }
+        
+        #expect(list.empty())
+    }
+}