fix(tests): Improve decorator tests and add LitElement component tests for better validation

test/test-decorators.ts

@@ -0,0 +1,41 @@
+// Test file to verify decorator functionality
+function sealed(constructor: Function) {
+  Object.seal(constructor);
+  Object.seal(constructor.prototype);
+}
+
+@sealed
+class TestClass {
+  name = 'test';
+  
+  modify() {
+    this.name = 'modified';
+  }
+}
+
+// Test that the class is sealed
+const instance = new TestClass();
+console.log('Initial name:', instance.name);
+
+// This should work (modifying existing property)
+instance.modify();
+console.log('Modified name:', instance.name);
+
+// This should fail silently in non-strict mode or throw in strict mode
+try {
+  (instance as any).newProperty = 'should not work';
+  console.log('Adding new property:', (instance as any).newProperty);
+} catch (e) {
+  console.log('Error adding property (expected):', e.message);
+}
+
+// Test that we can't add to prototype
+try {
+  (TestClass.prototype as any).newMethod = function() {};
+  console.log('Prototype is NOT sealed (unexpected)');
+} catch (e) {
+  console.log('Prototype is sealed (expected)');
+}
+
+console.log('Is TestClass sealed?', Object.isSealed(TestClass));
+console.log('Is TestClass.prototype sealed?', Object.isSealed(TestClass.prototype));