Invercargill/src/tests/Integration/Expressions.vala

using Invercargill;
using Invercargill.DataStructures;
using Invercargill.Expressions;

class ExprTestPerson : Object {
    public string name { get; set; }
    public int age { get; set; }
    public int rank { get; set; }
    public bool is_important { get; set; }
    
    public ExprTestPerson(string name, int age, int rank = 0, bool is_important = false) {
        this.name = name;
        this.age = age;
        this.rank = rank;
        this.is_important = is_important;
    }
}

class ExprTestContainer : Object {
    public int min_rank { get; set; }
    public Enumerable<ExprTestPerson> values { get; set; }
    
    public ExprTestContainer(int min_rank, Enumerable<ExprTestPerson> values) {
        this.min_rank = min_rank;
        this.values = values;
    }
}

void expression_tests() {

    // ==================== Literal Tests ====================

    Test.add_func("/invercargill/expressions/literal_int", () => {
        var expr = new LiteralExpression(new NativeElement<int>(42));
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int value;
        assert(result.try_get_as<int>(out value));
        assert(value == 42);
    });

    Test.add_func("/invercargill/expressions/literal_string", () => {
        var expr = new LiteralExpression(new NativeElement<string>("hello"));
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "hello");
    });

    Test.add_func("/invercargill/expressions/literal_bool", () => {
        var expr = new LiteralExpression(new NativeElement<bool>(true));
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/literal_null", () => {
        var expr = new LiteralExpression(new NullElement());
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        assert(result.is_null());
    });

    // ==================== Variable Tests ====================

    Test.add_func("/invercargill/expressions/variable", () => {
        var expr = new VariableExpression("x");
        var props = new PropertyDictionary();
        props.set("x", new NativeElement<int>(10));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int value;
        assert(result.try_get_as<int>(out value));
        assert(value == 10);
    });

    // ==================== Binary Comparison Tests ====================

    Test.add_func("/invercargill/expressions/binary_equals", () => {
        var expr = new BinaryExpression(
            new LiteralExpression(new NativeElement<int>(5)),
            new LiteralExpression(new NativeElement<int>(5)),
            BinaryOperator.EQUAL
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/binary_not_equals", () => {
        var expr = new BinaryExpression(
            new LiteralExpression(new NativeElement<int>(5)),
            new LiteralExpression(new NativeElement<int>(3)),
            BinaryOperator.NOT_EQUAL
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/binary_greater_than", () => {
        var expr = new BinaryExpression(
            new LiteralExpression(new NativeElement<int>(5)),
            new LiteralExpression(new NativeElement<int>(3)),
            BinaryOperator.GREATER_THAN
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/binary_less_than", () => {
        var expr = new BinaryExpression(
            new LiteralExpression(new NativeElement<int>(3)),
            new LiteralExpression(new NativeElement<int>(5)),
            BinaryOperator.LESS_THAN
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    // ==================== Binary Logical Tests ====================

    Test.add_func("/invercargill/expressions/binary_and", () => {
        var expr = new BinaryExpression(
            new LiteralExpression(new NativeElement<bool>(true)),
            new LiteralExpression(new NativeElement<bool>(true)),
            BinaryOperator.AND
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/binary_or", () => {
        var expr = new BinaryExpression(
            new LiteralExpression(new NativeElement<bool>(false)),
            new LiteralExpression(new NativeElement<bool>(true)),
            BinaryOperator.OR
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    // ==================== Binary Arithmetic Tests ====================

    Test.add_func("/invercargill/expressions/binary_arithmetic_add", () => {
        var expr = new BinaryExpression(
            new LiteralExpression(new NativeElement<int>(5)),
            new LiteralExpression(new NativeElement<int>(3)),
            BinaryOperator.ADD
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int64? value;
        assert(result.try_get_as<int64?>(out value));
        assert(value == 8);
    });

    Test.add_func("/invercargill/expressions/binary_arithmetic_subtract", () => {
        var expr = new BinaryExpression(
            new LiteralExpression(new NativeElement<int>(5)),
            new LiteralExpression(new NativeElement<int>(3)),
            BinaryOperator.SUBTRACT
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int64? value;
        assert(result.try_get_as<int64?>(out value));
        assert(value == 2);
    });

    Test.add_func("/invercargill/expressions/binary_arithmetic_multiply", () => {
        var expr = new BinaryExpression(
            new LiteralExpression(new NativeElement<int>(5)),
            new LiteralExpression(new NativeElement<int>(3)),
            BinaryOperator.MULTIPLY
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int64? value;
        assert(result.try_get_as<int64?>(out value));
        assert(value == 15);
    });

    Test.add_func("/invercargill/expressions/binary_arithmetic_divide", () => {
        var expr = new BinaryExpression(
            new LiteralExpression(new NativeElement<int>(15)),
            new LiteralExpression(new NativeElement<int>(3)),
            BinaryOperator.DIVIDE
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int64? value;
        assert(result.try_get_as<int64?>(out value));
        assert(value == 5);
    });

    Test.add_func("/invercargill/expressions/binary_arithmetic_modulo", () => {
        var expr = new BinaryExpression(
            new LiteralExpression(new NativeElement<int>(17)),
            new LiteralExpression(new NativeElement<int>(5)),
            BinaryOperator.MODULO
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int64? value;
        assert(result.try_get_as<int64?>(out value));
        assert(value == 2);
    });

    // ==================== Unary Tests ====================

    Test.add_func("/invercargill/expressions/unary_negate", () => {
        var expr = new UnaryExpression(
            UnaryOperator.NEGATE,
            new LiteralExpression(new NativeElement<int>(5))
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int64? value;
        assert(result.try_get_as<int64?>(out value));
        assert(value == -5);
    });

    Test.add_func("/invercargill/expressions/unary_not", () => {
        var expr = new UnaryExpression(
            UnaryOperator.NOT,
            new LiteralExpression(new NativeElement<bool>(false))
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    // ==================== Ternary Tests ====================

    Test.add_func("/invercargill/expressions/ternary_true", () => {
        var expr = new TernaryExpression(
            new LiteralExpression(new NativeElement<bool>(true)),
            new LiteralExpression(new NativeElement<string>("yes")),
            new LiteralExpression(new NativeElement<string>("no"))
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "yes");
    });

    Test.add_func("/invercargill/expressions/ternary_false", () => {
        var expr = new TernaryExpression(
            new LiteralExpression(new NativeElement<bool>(false)),
            new LiteralExpression(new NativeElement<string>("yes")),
            new LiteralExpression(new NativeElement<string>("no"))
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "no");
    });

    // ==================== Property Access Tests ====================

    Test.add_func("/invercargill/expressions/property_access", () => {
        var person = new ExprTestPerson("Alice", 30);
        var expr = new PropertyExpression(
            new VariableExpression("p"),
            "name"
        );
        var props = new PropertyDictionary();
        props.set("p", new NativeElement<ExprTestPerson?>(person));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Alice");
    });

    Test.add_func("/invercargill/expressions/nested_property_access", () => {
        var person = new ExprTestPerson("Bob", 25);
        var expr = new PropertyExpression(
            new VariableExpression("p"),
            "age"
        );
        var props = new PropertyDictionary();
        props.set("p", new NativeElement<ExprTestPerson>(person));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int value;
        assert(result.try_get_as<int>(out value));
        assert(value == 25);
    });

    // ==================== Bracketed Tests ====================

    Test.add_func("/invercargill/expressions/bracketed_expression", () => {
        // (5 + 3) * 2 = 16
        var inner = new BracketedExpression(
            new BinaryExpression(
                new LiteralExpression(new NativeElement<int>(5)),
                new LiteralExpression(new NativeElement<int>(3)),
                BinaryOperator.ADD
            )
        );
        var expr = new BinaryExpression(
            inner,
            new LiteralExpression(new NativeElement<int>(2)),
            BinaryOperator.MULTIPLY
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int64? value;
        assert(result.try_get_as<int64?>(out value));
        assert(value == 16);
    });

    // ==================== Complex Expression Tests ====================

    Test.add_func("/invercargill/expressions/complex_expression", () => {
        // a > 5 && b < 10
        var expr = new BinaryExpression(
            new BinaryExpression(
                new VariableExpression("a"),
                new LiteralExpression(new NativeElement<int>(5)),
                BinaryOperator.GREATER_THAN
            ),
            new BinaryExpression(
                new VariableExpression("b"),
                new LiteralExpression(new NativeElement<int>(10)),
                BinaryOperator.LESS_THAN
            ),
            BinaryOperator.AND
        );
        var props = new PropertyDictionary();
        props.set("a", new NativeElement<int>(7));
        props.set("b", new NativeElement<int>(8));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    // ==================== Lambda Tests ====================

    Test.add_func("/invercargill/expressions/lambda_basic", () => {
        // x => x > 5
        var body = new BinaryExpression(
            new VariableExpression("x"),
            new LiteralExpression(new NativeElement<int>(5)),
            BinaryOperator.GREATER_THAN
        );
        var expr = new LambdaExpression("x", body);
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        var lambda = result as LambdaElement;
        assert(lambda != null);
        assert(lambda.get_lambda().parameter_name == "x");
    });

    // ==================== Function Call Tests ====================

    Test.add_func("/invercargill/expressions/function_call_where", () => {
        // Create an enumerable of test persons
        var persons = new Series<ExprTestPerson>();
        persons.add(new ExprTestPerson("Alice", 30, 5));
        persons.add(new ExprTestPerson("Bob", 25, 3));
        persons.add(new ExprTestPerson("Charlie", 35, 7));
        
        // persons.where(p => p.rank > 4)
        var lambda_body = new BinaryExpression(
            new PropertyExpression(new VariableExpression("p"), "rank"),
            new LiteralExpression(new NativeElement<int>(4)),
            BinaryOperator.GREATER_THAN
        );
        var lambda = new LambdaExpression("p", lambda_body);
        
        var args = new Series<Expression>();
        args.add(lambda);
        
        var expr = new FunctionCallExpression(
            new LiteralExpression(new NativeElement<Enumerable<ExprTestPerson>?>(persons)),
            "where",
            args
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        Elements elements;
        assert(result.try_get_as<Elements>(out elements));
        
        // Should have 2 elements (Alice with rank 5, Charlie with rank 7)
        var count = 0;
        elements.iterate(e => count++);
        assert(count == 2);
    });

    Test.add_func("/invercargill/expressions/function_call_select", () => {
        // Create an enumerable of test persons
        var persons = new Series<ExprTestPerson>();
        persons.add(new ExprTestPerson("Alice", 30));
        persons.add(new ExprTestPerson("Bob", 25));
        
        // persons.select(p => p.name)
        var lambda_body = new PropertyExpression(new VariableExpression("p"), "name");
        var lambda = new LambdaExpression("p", lambda_body);
        
        var args = new Series<Expression>();
        args.add(lambda);
        
        var expr = new FunctionCallExpression(
            new LiteralExpression(new NativeElement<Enumerable<ExprTestPerson>>(persons)),
            "select",
            args
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        Elements elements;
        assert(result.try_get_as<Elements>(out elements));
        
        // Should have 2 string elements
        var names = new Series<string>();
        elements.iterate(e => {
            string? name;
            if(e.try_get_as<string>(out name)) {
                names.add(name);
            }
        });
        assert(names.length == 2);
        
        // Check names using iterate
        var idx = 0;
        names.iterate(n => {
            if (idx == 0) assert(n == "Alice");
            if (idx == 1) assert(n == "Bob");
            idx++;
        });
    });

    Test.add_func("/invercargill/expressions/function_call_first", () => {
        // Create an enumerable of test persons
        var persons = new Series<ExprTestPerson>();
        persons.add(new ExprTestPerson("Alice", 30));
        persons.add(new ExprTestPerson("Bob", 25));
        
        // persons.first()
        var expr = new FunctionCallExpression(
            new LiteralExpression(new NativeElement<Enumerable<ExprTestPerson>>(persons)),
            "first"
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        ExprTestPerson? person;
        assert(result.try_get_as<ExprTestPerson?>(out person));
        assert(person.name == "Alice");
    });

    Test.add_func("/invercargill/expressions/function_call_count", () => {
        // Create an enumerable of test persons
        var persons = new Series<ExprTestPerson>();
        persons.add(new ExprTestPerson("Alice", 30));
        persons.add(new ExprTestPerson("Bob", 25));
        persons.add(new ExprTestPerson("Charlie", 35));
        
        // persons.count()
        var expr = new FunctionCallExpression(
            new LiteralExpression(new NativeElement<Enumerable<ExprTestPerson>>(persons)),
            "count"
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int64? count;
        assert(result.try_get_as<int64?>(out count));
        assert(count == 3);
    });

    Test.add_func("/invercargill/expressions/function_call_any", () => {
        // Create an enumerable of test persons
        var persons = new Series<ExprTestPerson>();
        persons.add(new ExprTestPerson("Alice", 30, 5));
        persons.add(new ExprTestPerson("Bob", 25, 3));
        
        // persons.any(p => p.rank > 4)
        var lambda_body = new BinaryExpression(
            new PropertyExpression(new VariableExpression("p"), "rank"),
            new LiteralExpression(new NativeElement<int>(4)),
            BinaryOperator.GREATER_THAN
        );
        var lambda = new LambdaExpression("p", lambda_body);
        
        var args = new Series<Expression>();
        args.add(lambda);
        
        var expr = new FunctionCallExpression(
            new LiteralExpression(new NativeElement<Enumerable<ExprTestPerson>?>(persons)),
            "any",
            args
        );
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool any;
        assert(result.try_get_as<bool>(out any));
        assert(any == true);
    });

    // ==================== Chained Function Tests ====================

    Test.add_func("/invercargill/expressions/chained_where_first", () => {
        // Create an enumerable of test persons
        var persons = new Series<ExprTestPerson>();
        persons.add(new ExprTestPerson("Alice", 30, 5));
        persons.add(new ExprTestPerson("Bob", 25, 3));
        persons.add(new ExprTestPerson("Charlie", 35, 7));
        
        // persons.where(p => p.rank > 4).first()
        var lambda_body = new BinaryExpression(
            new PropertyExpression(new VariableExpression("p"), "rank"),
            new LiteralExpression(new NativeElement<int>(4)),
            BinaryOperator.GREATER_THAN
        );
        var lambda = new LambdaExpression("p", lambda_body);
        
        var args = new Series<Expression>();
        args.add(lambda);
        
        var where_call = new FunctionCallExpression(
            new LiteralExpression(new NativeElement<Enumerable<ExprTestPerson>?>(persons)),
            "where",
            args
        );
        
        var first_call = new FunctionCallExpression(
            where_call,
            "first"
        );
        
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = first_call.evaluate(context);
        assert(result != null);
        
        ExprTestPerson? person;
        assert(result.try_get_as<ExprTestPerson?>(out person));
        assert(person.name == "Alice"); // First with rank > 4
    });

    // ==================== Closure Tests ====================

    Test.add_func("/invercargill/expressions/closure_capture", () => {
        // Test that lambda can capture variables from outer scope
        // threshold = 4
        // persons.where(p => p.rank > threshold)
        var persons = new Series<ExprTestPerson>();
        persons.add(new ExprTestPerson("Alice", 30, 5));
        persons.add(new ExprTestPerson("Bob", 25, 3));
        persons.add(new ExprTestPerson("Charlie", 35, 7));
        
        var threshold = 4;
        
        // Create context with threshold
        var props = new PropertyDictionary();
        props.set("threshold", new NativeElement<int>(threshold));
        var parent_context = new EvaluationContext(props);
        
        // Lambda body: p.rank > threshold
        var lambda_body = new BinaryExpression(
            new PropertyExpression(new VariableExpression("p"), "rank"),
            new VariableExpression("threshold"),
            BinaryOperator.GREATER_THAN
        );
        var lambda = new LambdaExpression("p", lambda_body);
        
        var args = new Series<Expression>();
        args.add(lambda);
        
        var expr = new FunctionCallExpression(
            new LiteralExpression(new NativeElement<Enumerable<ExprTestPerson>?>(persons)),
            "where",
            args
        );
        
        var result = expr.evaluate(parent_context);
        assert(result != null);
        
        Elements elements;
        assert(result.try_get_as<Elements>(out elements));
        
        // Should have 2 elements (Alice with rank 5, Charlie with rank 7)
        var count = 0;
        elements.iterate(e => count++);
        assert(count == 2);
    });

    // ==================== Parser Tests ====================

    Test.add_func("/invercargill/expressions/parser_literal_int", () => {
        var expr = ExpressionParser.parse("42");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int64? value;
        assert(result.try_get_as<int64?>(out value));
        assert(value == 42);
    });

    Test.add_func("/invercargill/expressions/parser_literal_string", () => {
        var expr = ExpressionParser.parse("\"hello\"");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "hello");
    });

    Test.add_func("/invercargill/expressions/parser_literal_bool", () => {
        var expr = ExpressionParser.parse("true");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/parser_variable", () => {
        var expr = ExpressionParser.parse("x");
        var props = new PropertyDictionary();
        props.set("x", new NativeElement<int>(10));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int value;
        assert(result.try_get_as<int>(out value));
        assert(value == 10);
    });

    Test.add_func("/invercargill/expressions/parser_binary_equals", () => {
        var expr = ExpressionParser.parse("5 == 5");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/parser_binary_arithmetic", () => {
        var expr = ExpressionParser.parse("5 + 3");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int64? value;
        assert(result.try_get_as<int64?>(out value));
        assert(value == 8);
    });

    Test.add_func("/invercargill/expressions/parser_binary_logical", () => {
        var expr = ExpressionParser.parse("true && false");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == false);
    });

    Test.add_func("/invercargill/expressions/parser_ternary", () => {
        var expr = ExpressionParser.parse("true ? \"yes\" : \"no\"");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "yes");
    });

    Test.add_func("/invercargill/expressions/parser_property_access", () => {
        var person = new ExprTestPerson("Alice", 30);
        var expr = ExpressionParser.parse("p.name");
        var props = new PropertyDictionary();
        props.set("p", new NativeElement<ExprTestPerson?>(person));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Alice");
    });

    Test.add_func("/invercargill/expressions/parser_bracketed", () => {
        // (5 + 3) * 2 = 16
        var expr = ExpressionParser.parse("(5 + 3) * 2");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int64? value;
        assert(result.try_get_as<int64?>(out value));
        assert(value == 16);
    });

    Test.add_func("/invercargill/expressions/parser_unary_negate", () => {
        var expr = ExpressionParser.parse("-5");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int64? value;
        assert(result.try_get_as<int64?>(out value));
        assert(value == -5);
    });

    Test.add_func("/invercargill/expressions/parser_unary_not", () => {
        var expr = ExpressionParser.parse("!false");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/parser_lambda", () => {
        var expr = ExpressionParser.parse("x => x > 5");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        var lambda = result as LambdaElement;
        assert(lambda != null);
        assert(lambda.get_lambda().parameter_name == "x");
    });

    Test.add_func("/invercargill/expressions/parser_complex", () => {
        // a > 5 && b < 10
        var expr = ExpressionParser.parse("a > 5 && b < 10");
        var props = new PropertyDictionary();
        props.set("a", new NativeElement<int>(7));
        props.set("b", new NativeElement<int>(8));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/parser_operator_precedence", () => {
        // 2 + 3 * 4 = 14 (not 20)
        var expr = ExpressionParser.parse("2 + 3 * 4");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int64? value;
        assert(result.try_get_as<int64?>(out value));
        assert(value == 14);
    });

    Test.add_func("/invercargill/expressions/parser_comparison_chain", () => {
        // Test chained comparisons with proper precedence
        var expr = ExpressionParser.parse("5 < 10 && 10 > 5");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    // ==================== Lot Literal Tests ====================

    Test.add_func("/invercargill/expressions/lot_literal_empty", () => {
        var expr = new LotLiteralExpression(new Expression[0]);
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        Enumerable<Object?>? lot;
        assert(result.try_get_as<Enumerable<Object?>>(out lot));
        assert(lot != null);
        
        var count = 0;
        foreach (var item in lot) {
            count++;
        }
        assert(count == 0);
    });

    Test.add_func("/invercargill/expressions/lot_literal_integers", () => {
        var elements = new Expression[3];
        elements[0] = new LiteralExpression(new NativeElement<int>(1));
        elements[1] = new LiteralExpression(new NativeElement<int>(2));
        elements[2] = new LiteralExpression(new NativeElement<int>(3));
        
        var expr = new LotLiteralExpression(elements);
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        Enumerable<int>? lot;
        assert(result.try_get_as<Enumerable<int>?>(out lot));
        assert(lot != null);
        
        var values = new Series<int>();
        foreach (var item in lot) {
            values.add(item);
        }
        
        assert(values.length == 3);
        
        var idx = 0;
        foreach (var val in values) {
            if (idx == 0) assert(val == 1);
            else if (idx == 1) assert(val == 2);
            else if (idx == 2) assert(val == 3);
            idx++;
        }
    });

    Test.add_func("/invercargill/expressions/lot_literal_strings", () => {
        var elements = new Expression[3];
        elements[0] = new LiteralExpression(new NativeElement<string>("a"));
        elements[1] = new LiteralExpression(new NativeElement<string>("b"));
        elements[2] = new LiteralExpression(new NativeElement<string>("c"));
        
        var expr = new LotLiteralExpression(elements);
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        Enumerable<string?>? lot;
        assert(result.try_get_as<Enumerable<string?>>(out lot));
        assert(lot != null);
        
        var values = new Series<string?>();
        foreach (var item in lot) {
            values.add(item);
        }
        
        assert(values.length == 3);
    });

    Test.add_func("/invercargill/expressions/lot_literal_parser", () => {
        var expr = ExpressionParser.parse("[1, 2, 3]");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        Enumerable<int>? lot;
        assert(result.try_get_as<Enumerable<int>?>(out lot));
        assert(lot != null);
        
        var count = 0;
        foreach (var item in lot) {
            count++;
        }
        assert(count == 3);
    });

    // ==================== Iterate Function Tests ====================

    Test.add_func("/invercargill/expressions/iterate_range", () => {
        var accessor = new IterateFunctionAccessor();
        var args = new Series<Element>();
        args.add(new NativeElement<int>(0));
        args.add(new NativeElement<int>(5));
        
        var result = accessor.call_function("range", args, new EvaluationContext(new PropertyDictionary()));
        assert(result != null);
        
        Enumerable<int>? range;
        assert(result.try_get_as<Enumerable<int>?>(out range));
        assert(range != null);
        
        var values = new Series<int>();
        foreach (var item in range) {
            values.add(item);
        }
        
        assert(values.length == 5);
    });

    Test.add_func("/invercargill/expressions/iterate_single", () => {
        var accessor = new IterateFunctionAccessor();
        var args = new Series<Element>();
        args.add(new NativeElement<int>(42));
        
        var result = accessor.call_function("single", args, new EvaluationContext(new PropertyDictionary()));
        assert(result != null);
        
        Enumerable<int>? single;
        assert(result.try_get_as<Enumerable<int>?>(out single));
        assert(single != null);
        
        var count = 0;
        foreach (var item in single) {
            assert(item == 42);
            count++;
        }
        assert(count == 1);
    });

    Test.add_func("/invercargill/expressions/iterate_nothing", () => {
        var accessor = new IterateFunctionAccessor();
        var args = new Series<Element>();
        
        var result = accessor.call_function("nothing", args, new EvaluationContext(new PropertyDictionary()));
        assert(result != null);
        
        Enumerable<Object?>? empty;
        assert(result.try_get_as<Enumerable<Object?>>(out empty));
        assert(empty != null);
        
        var count = 0;
        foreach (var item in empty) {
            count++;
        }
        assert(count == 0);
    });

    Test.add_func("/invercargill/expressions/iterate_range_with_step", () => {
        var accessor = new IterateFunctionAccessor();
        var args = new Series<Element>();
        args.add(new NativeElement<int>(0));
        args.add(new NativeElement<int>(10));
        args.add(new NativeElement<int>(2));
        
        var result = accessor.call_function("range", args, new EvaluationContext(new PropertyDictionary()));
        assert(result != null);
        
        Enumerable<int>? range;
        assert(result.try_get_as<Enumerable<int>?>(out range));
        assert(range != null);
        
        var values = new Series<int>();
        foreach (var item in range) {
            values.add(item);
        }
        
        assert(values.length == 5); // 0, 2, 4, 6, 8
    });

    Test.add_func("/invercargill/expressions/global_functions_element", () => {
        var accessor = new IterateFunctionAccessor();
        var global_element = new GlobalFunctionsElement(accessor);
        
        var props = new PropertyDictionary();
        props.set("Iterate", global_element);
        var context = new EvaluationContext(props);
        
        // Get the variable
        var expr = new VariableExpression("Iterate");
        var result = expr.evaluate(context);
        assert(result != null);
        
        GlobalFunctionsElement? retrieved;
        assert(result.try_get_as<GlobalFunctionsElement?>(out retrieved));
        assert(retrieved != null);
        assert(retrieved.accessor is IterateFunctionAccessor);
    });

    // ==================== Global Format Function Tests ====================

    Test.add_func("/invercargill/expressions/format_string", () => {
        // format("Hello, {{name}}!")
        var expr = ExpressionParser.parse("format(\"Hello, {{name}}!\")");
        var props = new PropertyDictionary();
        props.set("name", new NativeElement<string>("World"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Hello, World!");
    });

    Test.add_func("/invercargill/expressions/format_integer", () => {
        // format("Count: {{count}}")
        var expr = ExpressionParser.parse("format(\"Count: {{count}}\")");
        var props = new PropertyDictionary();
        props.set("count", new NativeElement<int>(42));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Count: 42");
    });

    Test.add_func("/invercargill/expressions/format_multiple", () => {
        // format("{{category}} #{{id}}: {{title}}")
        var expr = ExpressionParser.parse("format(\"{{category}} #{{id}}: {{title}}\")");
        var props = new PropertyDictionary();
        props.set("category", new NativeElement<string>("Item"));
        props.set("id", new NativeElement<int>(123));
        props.set("title", new NativeElement<string>("Test Product"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Item #123: Test Product");
    });

    Test.add_func("/invercargill/expressions/format_float", () => {
        // format("Price: {{price}}")
        var expr = ExpressionParser.parse("format(\"Price: {{price}}\")");
        var props = new PropertyDictionary();
        props.set("price", new NativeElement<double?>(19.99));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Price: 19.99");
    });

    Test.add_func("/invercargill/expressions/format_hex", () => {
        // Note: Handlebars format doesn't support hex formatting natively
        // Using stringify to convert the value
        var expr = ExpressionParser.parse("format(\"Hex: {{value}}\")");
        var props = new PropertyDictionary();
        props.set("value", new NativeElement<int>(255));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Hex: 255");
    });

    Test.add_func("/invercargill/expressions/format_percent", () => {
        // Test that \% produces literal % (escape sequence)
        var expr = ExpressionParser.parse("format(\"100\\% complete\")");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "100% complete");
    });

    Test.add_func("/invercargill/expressions/format_no_args", () => {
        // format("Just a string")
        var expr = ExpressionParser.parse("format(\"Just a string\")");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Just a string");
    });

    // ==================== Nested Property Access Parser Tests ====================

    Test.add_func("/invercargill/expressions/parser_nested_property_simple", () => {
        // Test: p.name (simple property access via parser - same as existing test but confirms it works)
        var person = new ExprTestPerson("Alice", 30);
        var expr = ExpressionParser.parse("p.name");
        var props = new PropertyDictionary();
        props.set("p", new NativeElement<ExprTestPerson?>(person));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Alice");
    });

    Test.add_func("/invercargill/expressions/parser_nested_property_deep", () => {
        // Test: container.min_rank (accessing property on a container object)
        var persons = new Series<ExprTestPerson>();
        persons.add(new ExprTestPerson("Alice", 30, 5));
        var container = new ExprTestContainer(3, persons);
        
        var expr = ExpressionParser.parse("container.min_rank");
        var props = new PropertyDictionary();
        props.set("container", new NativeElement<ExprTestContainer?>(container));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int value;
        assert(result.try_get_as<int>(out value));
        assert(value == 3);
    });

    Test.add_func("/invercargill/expressions/parser_nested_property_with_comparison", () => {
        // Test: p.age > 18 (property access in comparison)
        var person = new ExprTestPerson("Bob", 25);
        var expr = ExpressionParser.parse("p.age > 18");
        var props = new PropertyDictionary();
        props.set("p", new NativeElement<ExprTestPerson?>(person));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/parser_nested_property_in_lambda", () => {
        // Test: items.where(i => i.rank > 2) - nested property in lambda
        var persons = new Series<ExprTestPerson>();
        persons.add(new ExprTestPerson("Alice", 30, 5));
        persons.add(new ExprTestPerson("Bob", 25, 1));
        persons.add(new ExprTestPerson("Charlie", 35, 3));
        
        var expr = ExpressionParser.parse("items.where(i => i.rank > 2)");
        var props = new PropertyDictionary();
        props.set("items", new NativeElement<Enumerable<ExprTestPerson>?>(persons));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        Elements elements;
        assert(result.try_get_as<Elements>(out elements));
        
        var count = 0;
        elements.iterate(e => count++);
        assert(count == 2); // Alice (rank 5) and Charlie (rank 3)
    });

    Test.add_func("/invercargill/expressions/parser_nested_property_chained_functions", () => {
        // Test: items.where(i => i.rank > 2).first().name
        var persons = new Series<ExprTestPerson>();
        persons.add(new ExprTestPerson("Alice", 30, 5));
        persons.add(new ExprTestPerson("Bob", 25, 1));
        persons.add(new ExprTestPerson("Charlie", 35, 3));
        
        var expr = ExpressionParser.parse("items.where(i => i.rank > 2).first().name");
        var props = new PropertyDictionary();
        props.set("items", new NativeElement<Enumerable<ExprTestPerson>?>(persons));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Alice"); // First item with rank > 2
    });

    Test.add_func("/invercargill/expressions/parser_nested_property_closure", () => {
        // Test: items.where(i => i.rank > container.min_rank) - closure with nested property
        var persons = new Series<ExprTestPerson>();
        persons.add(new ExprTestPerson("Alice", 30, 5));
        persons.add(new ExprTestPerson("Bob", 25, 1));
        persons.add(new ExprTestPerson("Charlie", 35, 3));
        var container = new ExprTestContainer(2, persons);
        
        var expr = ExpressionParser.parse("container.values.where(i => i.rank > container.min_rank)");
        var props = new PropertyDictionary();
        props.set("container", new NativeElement<ExprTestContainer?>(container));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        Elements elements;
        assert(result.try_get_as<Elements>(out elements));
        
        var count = 0;
        elements.iterate(e => count++);
        assert(count == 2); // Alice (rank 5) and Charlie (rank 3), both > min_rank (2)
    });

    Test.add_func("/invercargill/expressions/parser_nested_property_ternary", () => {
        // Test: p.age >= 18 ? p.name + " is adult" : p.name + " is minor"
        var person = new ExprTestPerson("Bob", 25);
        var expr = ExpressionParser.parse("p.age >= 18 ? p.name + \" is adult\" : p.name + \" is minor\"");
        var props = new PropertyDictionary();
        props.set("p", new NativeElement<ExprTestPerson?>(person));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Bob is adult");
    });

    Test.add_func("/invercargill/expressions/parser_nested_property_arithmetic", () => {
        // Test: p.age + 5 (property in arithmetic)
        var person = new ExprTestPerson("Alice", 30);
        var expr = ExpressionParser.parse("p.age + 5");
        var props = new PropertyDictionary();
        props.set("p", new NativeElement<ExprTestPerson?>(person));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int64? value;
        assert(result.try_get_as<int64?>(out value));
        assert(value == 35);
    });

    Test.add_func("/invercargill/expressions/parser_nested_property_boolean", () => {
        // Test: p.is_important (boolean property)
        var person = new ExprTestPerson("Important", 30, 5, true);
        var expr = ExpressionParser.parse("p.is_important");
        var props = new PropertyDictionary();
        props.set("p", new NativeElement<ExprTestPerson?>(person));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/parser_nested_property_complex_expression", () => {
        // Complex expression from the requirements:
        // a.values.where(s => s.rank > a.min_rank).first().is_important
        var persons = new Series<ExprTestPerson>();
        persons.add(new ExprTestPerson("Alice", 30, 1, false));
        persons.add(new ExprTestPerson("Bob", 25, 5, true));
        persons.add(new ExprTestPerson("Charlie", 35, 3, false));
        var container = new ExprTestContainer(2, persons);
        
        var expr = ExpressionParser.parse("a.values.where(s => s.rank > a.min_rank).first().is_important");
        var props = new PropertyDictionary();
        props.set("a", new NativeElement<ExprTestContainer?>(container));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true); // Bob has rank 5 > min_rank 2, and is_important = true
    });

    // ==================== String Property Accessor Tests ====================

    Test.add_func("/invercargill/expressions/string_length", () => {
        var expr = ExpressionParser.parse("s.length");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>("hello"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        int value;
        assert(result.try_get_as<int>(out value));
        assert(value == 5);
    });

    Test.add_func("/invercargill/expressions/string_empty", () => {
        var expr = ExpressionParser.parse("s.empty");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>(""));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/string_is_null", () => {
        var expr = ExpressionParser.parse("s.is_null");
        var props = new PropertyDictionary();
        props.set("s", new NullElement());
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/string_is_empty_or_null", () => {
        // Test with empty string
        var expr = ExpressionParser.parse("s.is_empty_or_null");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>(""));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    // ==================== String Function Accessor Tests ====================

    Test.add_func("/invercargill/expressions/string_chomp", () => {
        var expr = ExpressionParser.parse("s.chomp()");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>("hello  "));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "hello");
    });

    Test.add_func("/invercargill/expressions/string_chug", () => {
        var expr = ExpressionParser.parse("s.chug()");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>("  hello"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "hello");
    });

    Test.add_func("/invercargill/expressions/string_upper", () => {
        var expr = ExpressionParser.parse("s.upper()");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>("hello"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "HELLO");
    });

    Test.add_func("/invercargill/expressions/string_lower", () => {
        var expr = ExpressionParser.parse("s.lower()");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>("HELLO"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "hello");
    });

    Test.add_func("/invercargill/expressions/string_contains", () => {
        var expr = ExpressionParser.parse("s.contains(\"ell\")");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>("hello"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/string_has_prefix", () => {
        var expr = ExpressionParser.parse("s.has_prefix(\"hel\")");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>("hello"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/string_has_suffix", () => {
        var expr = ExpressionParser.parse("s.has_suffix(\"llo\")");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>("hello"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/string_replace", () => {
        var expr = ExpressionParser.parse("s.replace(\"l\", \"x\")");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>("hello"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "hexxo");
    });

    Test.add_func("/invercargill/expressions/string_substring", () => {
        var expr = ExpressionParser.parse("s.substring(1, 3)");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>("hello"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "ell");
    });

    Test.add_func("/invercargill/expressions/string_split", () => {
        var expr = ExpressionParser.parse("s.split(\",\")");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>("a,b,c"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        Enumerable<string?>? parts;
        assert(result.try_get_as<Enumerable<string?>>(out parts));
        assert(parts != null);
        
        var count = 0;
        foreach (var part in parts) {
            count++;
        }
        assert(count == 3);
    });

    Test.add_func("/invercargill/expressions/string_char_at", () => {
        var expr = ExpressionParser.parse("s.char_at(1)");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>("hello"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "e");
    });

    Test.add_func("/invercargill/expressions/string_char_at_negative_index", () => {
        // Test negative index (from end)
        var expr = ExpressionParser.parse("s.char_at(-1)");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>("hello"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "o");
    });

    Test.add_func("/invercargill/expressions/string_char_at_out_of_bounds", () => {
        // Test out of bounds returns null
        var expr = ExpressionParser.parse("s.char_at(100)");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>("hello"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        assert(result.is_null());
    });

    Test.add_func("/invercargill/expressions/string_reverse", () => {
        var expr = ExpressionParser.parse("s.reverse()");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>("hello"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "olleh");
    });

    Test.add_func("/invercargill/expressions/string_chained_operations", () => {
        // Test chaining: s.chug().chomp().upper()
        var expr = ExpressionParser.parse("s.chug().chomp().upper()");
        var props = new PropertyDictionary();
        props.set("s", new NativeElement<string>("  hello  "));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "HELLO");
    });

    Test.add_func("/invercargill/expressions/string_in_complex_expression", () => {
        // Test string operations in a complex expression
        // name.chug().chomp().length > 3
        var expr = ExpressionParser.parse("name.chug().chomp().length > 3");
        var props = new PropertyDictionary();
        props.set("name", new NativeElement<string>("  hello  "));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    // ==================== Element.stringify() Tests ====================

    Test.add_func("/invercargill/expressions/element_stringify_null", () => {
        // Test null element → empty string
        var element = new NullElement();
        assert(element.stringify() == "");
    });

    Test.add_func("/invercargill/expressions/element_stringify_string", () => {
        // Test string element → returns the string
        var element = new NativeElement<string>("hello world");
        assert(element.stringify() == "hello world");
    });

    Test.add_func("/invercargill/expressions/element_stringify_string_null", () => {
        // Test null string element → empty string
        var element = new NullElement();
        assert(element.stringify() == "");
    });

    Test.add_func("/invercargill/expressions/element_stringify_int", () => {
        // Test int element → decimal representation
        var element = new NativeElement<int>(42);
        assert(element.stringify() == "42");
    });

    Test.add_func("/invercargill/expressions/element_stringify_int_negative", () => {
        // Test negative int element → decimal representation
        var element = new NativeElement<int>(-17);
        assert(element.stringify() == "-17");
    });

    Test.add_func("/invercargill/expressions/element_stringify_long", () => {
        // Test long element → decimal representation
        var element = new NativeElement<long>(123456789L);
        assert(element.stringify() == "123456789");
    });

    Test.add_func("/invercargill/expressions/element_stringify_int64", () => {
        // Test int64 element → decimal representation
        var element = new NativeElement<int64?>(9876543210LL);
        assert(element.stringify() == "9876543210");
    });

    Test.add_func("/invercargill/expressions/element_stringify_double", () => {
        // Test double element → decimal representation
        var element = new NativeElement<double?>(3.5);
        assert(element.stringify() == "3.5");
    });

    Test.add_func("/invercargill/expressions/element_stringify_float", () => {
        // Test float element → decimal representation
        var element = new NativeElement<float?>(2.5f);
        assert(element.stringify() == "2.5");
    });

    Test.add_func("/invercargill/expressions/element_stringify_bool_true", () => {
        // Test bool element true → "true"
        var element = new NativeElement<bool>(true);
        assert(element.stringify() == "true");
    });

    Test.add_func("/invercargill/expressions/element_stringify_bool_false", () => {
        // Test bool element false → "false"
        var element = new NativeElement<bool>(false);
        assert(element.stringify() == "false");
    });

    Test.add_func("/invercargill/expressions/element_stringify_object_fallback", () => {
        // Test other types → falls back to to_string()
        var person = new ExprTestPerson("Alice", 30);
        var element = new NativeElement<ExprTestPerson?>(person);
        // The default to_string() returns "Element[type_name()]"
        assert(element.stringify().contains("ExprTestPerson"));
    });

    // ==================== Handlebars format() Function Tests ====================

    Test.add_func("/invercargill/expressions/format_handlebars_simple", () => {
        // Simple variable interpolation: format("Hello, {{name}}!") with name="World"
        var expr = ExpressionParser.parse("format(\"Hello, {{name}}!\")");
        var props = new PropertyDictionary();
        props.set("name", new NativeElement<string>("World"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Hello, World!");
    });

    Test.add_func("/invercargill/expressions/format_handlebars_multiple", () => {
        // Multiple interpolations: format("{{a}} + {{b}} = {{c}}")
        var expr = ExpressionParser.parse("format(\"{{a}} + {{b}} = {{c}}\")");
        var props = new PropertyDictionary();
        props.set("a", new NativeElement<int>(2));
        props.set("b", new NativeElement<int>(3));
        props.set("c", new NativeElement<int>(5));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "2 + 3 = 5");
    });

    Test.add_func("/invercargill/expressions/format_handlebars_expression", () => {
        // Expression evaluation: format("Sum: {{a + b}}")
        var expr = ExpressionParser.parse("format(\"Sum: {{a + b}}\")");
        var props = new PropertyDictionary();
        props.set("a", new NativeElement<int>(10));
        props.set("b", new NativeElement<int>(32));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Sum: 42");
    });

    Test.add_func("/invercargill/expressions/format_handlebars_property_access", () => {
        // Property access: format("User: {{user.name}}")
        var person = new ExprTestPerson("Alice", 30);
        var expr = ExpressionParser.parse("format(\"User: {{user.name}}, Age: {{user.age}}\")");
        var props = new PropertyDictionary();
        props.set("user", new NativeElement<ExprTestPerson?>(person));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "User: Alice, Age: 30");
    });

    Test.add_func("/invercargill/expressions/format_handlebars_escape_braces", () => {
        // Escape sequences: format("Literal: \\{{name}}") → "Literal: {{name}}"
        // In Vala source: "\\\\{{" -> runtime string: "\\{{" -> parsed string: "\{{" -> format outputs: "{{"
        var expr = ExpressionParser.parse("format(\"Literal: \\\\{{name}}\")");
        var props = new PropertyDictionary();
        props.set("name", new NativeElement<string>("World"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Literal: {{name}}");
    });

    Test.add_func("/invercargill/expressions/format_handlebars_escape_backslash", () => {
        // Escape backslash: format("Path: C:\\\\Users") → "Path: C:\Users"
        // In Vala source: "\\\\\\\\" -> runtime string: "\\\\" -> parsed string: "\\" -> format outputs: "\"
        // To get a literal backslash in the format output, we need "\\" in the parsed string
        var expr = ExpressionParser.parse("format(\"Path: C:\\\\\\\\Users\")");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Path: C:\\Users");
    });

    Test.add_func("/invercargill/expressions/format_handlebars_empty_expression", () => {
        // Empty expression: format("Empty: {{}}") → "Empty: "
        var expr = ExpressionParser.parse("format(\"Empty: {{}}\")");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Empty: ");
    });

    Test.add_func("/invercargill/expressions/format_handlebars_whitespace_in_expression", () => {
        // Whitespace in expression should be trimmed
        var expr = ExpressionParser.parse("format(\"Value: {{  name  }}\")");
        var props = new PropertyDictionary();
        props.set("name", new NativeElement<string>("test"));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Value: test");
    });

    Test.add_func("/invercargill/expressions/format_handlebars_bool", () => {
        // Boolean interpolation
        var expr = ExpressionParser.parse("format(\"Is active: {{active}}\")");
        var props = new PropertyDictionary();
        props.set("active", new NativeElement<bool>(true));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Is active: true");
    });

    Test.add_func("/invercargill/expressions/format_handlebars_null", () => {
        // Null interpolation → empty string
        var expr = ExpressionParser.parse("format(\"Value: '{{value}}'\")");
        var props = new PropertyDictionary();
        props.set("value", new NullElement());
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Value: ''");
    });

    Test.add_func("/invercargill/expressions/format_handlebars_no_placeholders", () => {
        // Template with no placeholders
        var expr = ExpressionParser.parse("format(\"Just a plain string\")");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Just a plain string");
    });

    Test.add_func("/invercargill/expressions/format_handlebars_ternary", () => {
        // Ternary expression in handlebars
        var expr = ExpressionParser.parse("format(\"Status: {{active ? \\\"active\\\" : \\\"inactive\\\"}}\")");
        var props = new PropertyDictionary();
        props.set("active", new NativeElement<bool>(true));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Status: active");
    });

    // ==================== stringify() Global Function Tests ====================

    Test.add_func("/invercargill/expressions/stringify_single_int", () => {
        // Single argument: stringify(42) → "42"
        var expr = ExpressionParser.parse("stringify(42)");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "42");
    });

    Test.add_func("/invercargill/expressions/stringify_single_string", () => {
        // Single string argument: stringify("hello") → "hello"
        var expr = ExpressionParser.parse("stringify(\"hello\")");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "hello");
    });

    Test.add_func("/invercargill/expressions/stringify_multiple_strings", () => {
        // Multiple arguments: stringify("Hello", " ", "World") → "Hello World"
        var expr = ExpressionParser.parse("stringify(\"Hello\", \" \", \"World\")");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Hello World");
    });

    Test.add_func("/invercargill/expressions/stringify_mixed_types", () => {
        // Mixed types: stringify(1, " + ", 2, " = ", 3) → "1 + 2 = 3"
        var expr = ExpressionParser.parse("stringify(1, \" + \", 2, \" = \", 3)");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "1 + 2 = 3");
    });

    Test.add_func("/invercargill/expressions/stringify_no_arguments", () => {
        // No arguments: stringify() → ""
        var expr = ExpressionParser.parse("stringify()");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "");
    });

    Test.add_func("/invercargill/expressions/stringify_null", () => {
        // Null argument: stringify(null) → ""
        var expr = ExpressionParser.parse("stringify(null)");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "");
    });

    Test.add_func("/invercargill/expressions/stringify_bool", () => {
        // Boolean arguments: stringify(true, " or ", false) → "true or false"
        var expr = ExpressionParser.parse("stringify(true, \" or \", false)");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "true or false");
    });

    Test.add_func("/invercargill/expressions/stringify_variable", () => {
        // Stringify with variable
        var expr = ExpressionParser.parse("stringify(\"The answer is: \", answer)");
        var props = new PropertyDictionary();
        props.set("answer", new NativeElement<int>(42));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "The answer is: 42");
    });

    Test.add_func("/invercargill/expressions/stringify_expression", () => {
        // Stringify with expression evaluation
        var expr = ExpressionParser.parse("stringify(\"Sum: \", 2 + 3)");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Sum: 5");
    });

    Test.add_func("/invercargill/expressions/stringify_float", () => {
        // Stringify floating point number
        var expr = ExpressionParser.parse("stringify(3.5)");
        var props = new PropertyDictionary();
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "3.5");
    });

    // ==================== Lot Length Formatting Bug Tests ====================
    // BUG: format strings referencing lot.length print large random numbers
    // Root cause: NativeElement.try_get_as<TOut>() generic value type casts
    // may read garbage memory when T=uint

    Test.add_func("/invercargill/expressions/format_lot_length_bug", () => {
        // Create a Vector with 3 elements (known length)
        var vector = new Vector<int>();
        vector.add(1);
        vector.add(2);
        vector.add(3);
        
        // Use format string with {{lot.length}}
        var expr = ExpressionParser.parse("format(\"Length: {{lot.length}}\")");
        var props = new PropertyDictionary();
        props.set("lot", new NativeElement<Lot<int>?>(vector));
        var context = new EvaluationContext(props);
        
        var result = expr.evaluate(context);
        assert(result != null);
        
        string value;
        assert(result.try_get_as<string>(out value));
        // This assertion should fail due to the bug - it will show a large
        // random number instead of "3"
        assert(value == "Length: 3");
    });

    // ==================== Parameterized Expression Tests ====================

    Test.add_func("/invercargill/expressions/parameter_single", () => {
        // Single parameter: $0 > 5
        var params = new Series<Element>();
        params.add(new NativeElement<int>(10));
        var expr = ExpressionParser.parse_with_params("$0 > 5", params);
        var context = new EvaluationContext(new PropertyDictionary());
        var result = expr.evaluate(context);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/parameter_multiple", () => {
        // Multiple parameters: $0 + $1
        var params = new Series<Element>();
        params.add(new NativeElement<int>(3));
        params.add(new NativeElement<int>(4));
        var expr = ExpressionParser.parse_with_params("$0 + $1", params);
        var context = new EvaluationContext(new PropertyDictionary());
        var result = expr.evaluate(context);
        
        int64? value;
        assert(result.try_get_as<int64?>(out value));
        assert(value == 7);
    });

    Test.add_func("/invercargill/expressions/parameter_with_variable", () => {
        // Parameter with variable: x > $0
        var params = new Series<Element>();
        params.add(new NativeElement<int>(5));
        var expr = ExpressionParser.parse_with_params("x > $0", params);
        var props = new PropertyDictionary();
        props.set("x", new NativeElement<int>(10));
        var context = new EvaluationContext(props);
        var result = expr.evaluate(context);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/parameter_string", () => {
        // String parameter: $0 == "hello"
        var params = new Series<Element>();
        params.add(new NativeElement<string>("hello"));
        var expr = ExpressionParser.parse_with_params("$0 == \"hello\"", params);
        var context = new EvaluationContext(new PropertyDictionary());
        var result = expr.evaluate(context);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/parameter_complex_object", () => {
        // Complex object parameter: $0.name
        var person = new ExprTestPerson("Alice", 30);
        var params = new Series<Element>();
        params.add(new NativeElement<ExprTestPerson>(person));
        var expr = ExpressionParser.parse_with_params("$0.name", params);
        var context = new EvaluationContext(new PropertyDictionary());
        var result = expr.evaluate(context);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "Alice");
    });

    Test.add_func("/invercargill/expressions/parameter_in_ternary", () => {
        // Parameter in ternary: $0 ? "yes" : "no"
        var params = new Series<Element>();
        params.add(new NativeElement<bool>(true));
        var expr = ExpressionParser.parse_with_params("$0 ? \"yes\" : \"no\"", params);
        var context = new EvaluationContext(new PropertyDictionary());
        var result = expr.evaluate(context);
        
        string value;
        assert(result.try_get_as<string>(out value));
        assert(value == "yes");
    });

    Test.add_func("/invercargill/expressions/parameter_in_lambda", () => {
        // Parameter in lambda: items.where(i => i.rank > $0)
        var persons = new Series<ExprTestPerson>();
        persons.add(new ExprTestPerson("Alice", 30, 5));
        persons.add(new ExprTestPerson("Bob", 25, 1));
        persons.add(new ExprTestPerson("Charlie", 35, 3));
        
        var params = new Series<Element>();
        params.add(new NativeElement<int>(2));
        var expr = ExpressionParser.parse_with_params("items.where(i => i.rank > $0)", params);
        var props = new PropertyDictionary();
        props.set("items", new NativeElement<Enumerable<ExprTestPerson>?>(persons));
        var context = new EvaluationContext(props);
        var result = expr.evaluate(context);
        
        Elements elements;
        assert(result.try_get_as<Elements>(out elements));
        
        var count = 0;
        elements.iterate(e => count++);
        assert(count == 2); // Alice (rank 5) and Charlie (rank 3)
    });

    Test.add_func("/invercargill/expressions/parameter_range_check", () => {
        // Range check with two parameters: $0 <= x && x <= $1
        var params = new Series<Element>();
        params.add(new NativeElement<int>(0));
        params.add(new NativeElement<int>(100));
        var expr = ExpressionParser.parse_with_params("$0 <= x && x <= $1", params);
        var props = new PropertyDictionary();
        props.set("x", new NativeElement<int>(50));
        var context = new EvaluationContext(props);
        var result = expr.evaluate(context);
        
        bool value;
        assert(result.try_get_as<bool>(out value));
        assert(value == true);
    });

    Test.add_func("/invercargill/expressions/parameter_expression_string", () => {
        // Test to_expression_string returns $N format
        var expr = new ParameterExpression(0, new NativeElement<int>(42));
        assert(expr.to_expression_string() == "$0");
    });

    Test.add_func("/invercargill/expressions/parameter_expression_type", () => {
        // Test expression_type is PARAMETER
        var expr = new ParameterExpression(0, new NativeElement<int>(42));
        assert(expr.expression_type == ExpressionType.PARAMETER);
    });
}