// Comprehensive test suite for cell runtime stability
// Tests all core features before implementing performance optimizations
// (bytecode passes, ICs, quickening, tail call optimization)
//
return {
    // ============================================================================
    // ARITHMETIC OPERATORS - Numbers
    // ============================================================================

    test_number_addition: function() {
        if (1 + 2 != 3) throw "basic addition failed"
        if (0 + 0 != 0) throw "zero addition failed"
        if (-5 + 3 != -2) throw "negative addition failed"
        if (0.1 + 0.2 - 0.3 > 0.0001) throw "float addition precision issue"
    },

    test_number_subtraction: function() {
        if (5 - 3 != 2) throw "basic subtraction failed"
        if (0 - 5 != -5) throw "zero subtraction failed"
        if (-5 - -3 != -2) throw "negative subtraction failed"
    },

    test_number_multiplication: function() {
        if (3 * 4 != 12) throw "basic multiplication failed"
        if (0 * 100 != 0) throw "zero multiplication failed"
        if (-3 * 4 != -12) throw "negative multiplication failed"
        if (-3 * -4 != 12) throw "double negative multiplication failed"
    },

    test_number_division: function() {
        if (12 / 4 != 3) throw "basic division failed"
        if (1 / 2 != 0.5) throw "fractional division failed"
        if (-12 / 4 != -3) throw "negative division failed"
        if (12 / -4 != -3) throw "division by negative failed"
    },

    test_number_modulo: function() {
        if (10 % 3 != 1) throw "basic modulo failed"
        if (10 % 5 != 0) throw "even modulo failed"
        if (-10 % 3 != -1) throw "negative modulo failed"
    },

    test_number_exponentiation: function() {
        if (2 ** 3 != 8) throw "basic exponentiation failed"
        if (5 ** 0 != 1) throw "zero exponent failed"
        if (2 ** -1 != 0.5) throw "negative exponent failed"
    },

    // ============================================================================
    // STRING OPERATORS
    // ============================================================================

    test_string_plus_string_works: function() {
        var x = "hello" + " world"
        if (x != "hello world") throw "string + string should work"
    },

    test_string_concatenation_empty: function() {
        if ("" + "" != "") throw "empty string concatenation failed"
        if ("hello" + "" != "hello") throw "concatenation with empty string failed"
        if ("" + "world" != "world") throw "empty + string failed"
    },

    // ============================================================================
    // TYPE MIXING SHOULD THROW
    // ============================================================================

    test_number_plus_string_throws: function() {
        var caught = false
        try {
            var x = 1 + "hello"
        } catch (e) {
            caught = true
        }
        if (!caught) throw "number + string should throw"
    },

    test_string_plus_number_throws: function() {
        var caught = false
        try {
            var x = "hello" + 1
        } catch (e) {
            caught = true
        }
        if (!caught) throw "string + number should throw"
    },

    test_object_plus_string_throws: function() {
        var caught = false
        try {
            var x = {} + "hello"
        } catch (e) {
            caught = true
        }
        if (!caught) throw "object + string should throw"
    },

    test_string_plus_object_throws: function() {
        var caught = false
        try {
            var x = "hello" + {}
        } catch (e) {
            caught = true
        }
        if (!caught) throw "string + object should throw"
    },

    test_array_plus_string_throws: function() {
        var caught = false
        try {
            var x = [] + "hello"
        } catch (e) {
            caught = true
        }
        if (!caught) throw "array + string should throw"
    },

    test_string_plus_array_throws: function() {
        var caught = false
        try {
            var x = "hello" + []
        } catch (e) {
            caught = true
        }
        if (!caught) throw "string + array should throw"
    },

    test_boolean_plus_string_throws: function() {
        var caught = false
        try {
            var x = true + "hello"
        } catch (e) {
            caught = true
        }
        if (!caught) throw "boolean + string should throw"
    },

    test_string_plus_boolean_throws: function() {
        var caught = false
        try {
            var x = "hello" + false
        } catch (e) {
            caught = true
        }
        if (!caught) throw "string + boolean should throw"
    },

    test_null_plus_string_throws: function() {
        var caught = false
        try {
            var x = null + "hello"
        } catch (e) {
            caught = true
        }
        if (!caught) throw "null + string should throw"
    },

    test_string_plus_null_throws: function() {
        var caught = false
        try {
            var x = "hello" + null
        } catch (e) {
            caught = true
        }
        if (!caught) throw "string + null should throw"
    },

    // ============================================================================
    // COMPARISON OPERATORS
    // ============================================================================

    test_equality_numbers: function() {
        if (!(5 == 5)) throw "number equality failed"
        if (5 == 6) throw "number inequality detection failed"
        if (!(0 == 0)) throw "zero equality failed"
        if (!(-5 == -5)) throw "negative equality failed"
    },

    test_inequality_numbers: function() {
        if (5 != 5) throw "number inequality failed"
        if (!(5 != 6)) throw "number difference detection failed"
    },

    test_less_than: function() {
        if (!(3 < 5)) throw "less than failed"
        if (5 < 3) throw "not less than failed"
        if (5 < 5) throw "equal not less than failed"
    },

    test_less_than_or_equal: function() {
        if (!(3 <= 5)) throw "less than or equal failed"
        if (!(5 <= 5)) throw "equal in less than or equal failed"
        if (6 <= 5) throw "not less than or equal failed"
    },

    test_greater_than: function() {
        if (!(5 > 3)) throw "greater than failed"
        if (3 > 5) throw "not greater than failed"
        if (5 > 5) throw "equal not greater than failed"
    },

    test_greater_than_or_equal: function() {
        if (!(5 >= 3)) throw "greater than or equal failed"
        if (!(5 >= 5)) throw "equal in greater than or equal failed"
        if (3 >= 5) throw "not greater than or equal failed"
    },

    test_string_equality: function() {
        if (!("hello" == "hello")) throw "string equality failed"
        if ("hello" == "world") throw "string inequality detection failed"
        if (!("" == "")) throw "empty string equality failed"
    },

    test_null_equality: function() {
        if (!(null == null)) throw "null equality failed"
        if (null == 0) throw "null should not equal 0"
        if (null == false) throw "null should not equal false"
        if (null == "") throw "null should not equal empty string"
    },

    test_boolean_equality: function() {
        if (!(true == true)) throw "true equality failed"
        if (!(false == false)) throw "false equality failed"
        if (true == false) throw "boolean inequality detection failed"
    },

    // ============================================================================
    // LOGICAL OPERATORS
    // ============================================================================

    test_logical_and: function() {
        if (!(true && true)) throw "true && true failed"
        if (true && false) throw "true && false failed"
        if (false && true) throw "false && true failed"
        if (false && false) throw "false && false failed"
    },

    test_logical_or: function() {
        if (!(true || true)) throw "true || true failed"
        if (!(true || false)) throw "true || false failed"
        if (!(false || true)) throw "false || true failed"
        if (false || false) throw "false || false failed"
    },

    test_logical_not: function() {
        if (!(!false)) throw "!false failed"
        if (!true) throw "!true failed"
    },

    test_short_circuit_and: function() {
        var called = false
        var fn = function() { called = true; return true }
        var result = false && fn()
        if (called) throw "AND should short circuit"
    },

    test_short_circuit_or: function() {
        var called = false
        var fn = function() { called = true; return false }
        var result = true || fn()
        if (called) throw "OR should short circuit"
    },

    // ============================================================================
    // BITWISE OPERATORS
    // ============================================================================

    test_bitwise_and: function() {
        if ((5 & 3) != 1) throw "bitwise AND failed"
        if ((12 & 10) != 8) throw "bitwise AND failed"
    },

    test_bitwise_or: function() {
        if ((5 | 3) != 7) throw "bitwise OR failed"
        if ((12 | 10) != 14) throw "bitwise OR failed"
    },

    test_bitwise_xor: function() {
        if ((5 ^ 3) != 6) throw "bitwise XOR failed"
        if ((12 ^ 10) != 6) throw "bitwise XOR failed"
    },

    test_bitwise_not: function() {
        if (~5 != -6) throw "bitwise NOT failed"
        if (~0 != -1) throw "bitwise NOT of zero failed"
    },

    test_left_shift: function() {
        if ((5 << 2) != 20) throw "left shift failed"
        if ((1 << 3) != 8) throw "left shift failed"
    },

    test_right_shift: function() {
        if ((20 >> 2) != 5) throw "right shift failed"
        if ((8 >> 3) != 1) throw "right shift failed"
    },

    test_unsigned_right_shift: function() {
        if ((-1 >>> 1) != 2147483647) throw "unsigned right shift failed"
    },

    // ============================================================================
    // VARIABLE DECLARATIONS AND SCOPING
    // ============================================================================

    test_var_declaration: function() {
        var x = 5
        if (x != 5) throw "var declaration failed"
    },

    test_var_reassignment: function() {
        var x = 5
        x = 10
        if (x != 10) throw "var reassignment failed"
    },

    // ============================================================================
    // VAR BLOCK SCOPING (var now behaves like let)
    // ============================================================================

    test_var_block_scope_basic: function() {
        var x = 1
        {
            var x = 2
            if (x != 2) throw "var should be block scoped - inner scope failed"
        }
        if (x != 1) throw "var should be block scoped - outer scope affected"
    },

    test_var_block_scope_if: function() {
        var x = 1
        if (true) {
            var x = 2
            if (x != 2) throw "var in if block should be scoped"
        }
        if (x != 1) throw "var in if block should not affect outer scope"
    },

    test_var_block_scope_for: function() {
        var x = 1
        for (var i = 0; i < 1; i = i + 1) {
            var x = 2
            if (x != 2) throw "var in for block should be scoped"
        }
        if (x != 1) throw "var in for block should not affect outer scope"
    },

    test_var_for_loop_iterator_scope: function() {
        var sum = 0
        for (var i = 0; i < 3; i = i + 1) {
            sum = sum + i
        }
        if (sum != 3) throw "for loop should work with block scoped var"
        var caught = false
        try {
            var y = i
        } catch (e) {
            caught = true
        }
        if (!caught) throw "for loop iterator should not leak to outer scope"
    },

    test_var_nested_blocks: function() {
        var x = 1
        {
            var x = 2
            {
                var x = 3
                if (x != 3) throw "var in nested block level 2 failed"
            }
            if (x != 2) throw "var in nested block level 1 failed"
        }
        if (x != 1) throw "var in nested blocks outer scope failed"
    },

    test_var_redeclaration_different_scope: function() {
        var x = 1
        {
            var x = 2
        }
        if (x != 1) throw "var in different scope should not affect outer"
    },

    test_var_switch_scope: function() {
        var x = 1
        switch (1) {
            case 1:
                var x = 2
                if (x != 2) throw "var in switch should be block scoped"
                break
        }
        if (x != 1) throw "var in switch should not affect outer scope"
    },

    test_var_while_scope: function() {
        var x = 1
        var count = 0
        while (count < 1) {
            var x = 2
            if (x != 2) throw "var in while should be block scoped"
            count = count + 1
        }
        if (x != 1) throw "var in while should not affect outer scope"
    },

    test_var_no_initialization: function() {
        {
            var x
            if (x != null) throw "uninitialized var should be null"
        }
    },

    test_multiple_var_declaration: function() {
        var a = 1, b = 2, c = 3
        if (a != 1 || b != 2 || c != 3) throw "multiple var declaration failed"
    },

    test_function_scope: function() {
        var outer = "outer"
        var fn = function() {
            var inner = "inner"
            return inner
        }
        if (fn() != "inner") throw "function scope failed"
    },

    // ============================================================================
    // FUNCTION CALLS
    // ============================================================================

    test_function_call_no_args: function() {
        var fn = function() { return 42 }
        if (fn() != 42) throw "function call with no args failed"
    },

    test_function_call_one_arg: function() {
        var fn = function(x) { return x * 2 }
        if (fn(5) != 10) throw "function call with one arg failed"
    },

    test_function_call_multiple_args: function() {
        var fn = function(a, b, c) { return a + b + c }
        if (fn(1, 2, 3) != 6) throw "function call with multiple args failed"
    },

    test_function_call_extra_args: function() {
        var fn = function(a, b) { return a + b }
        if (fn(1, 2, 3, 4) != 3) throw "function call with extra args failed"
    },

    test_function_call_missing_args: function() {
        var fn = function(a, b, c) { return (a || 0) + (b || 0) + (c || 0) }
        if (fn(1) != 1) throw "function call with missing args failed"
    },

    test_function_return: function() {
        var fn = function() { return 5 }
        if (fn() != 5) throw "function return failed"
    },

    test_function_return_early: function() {
        var fn = function() {
            return 5
            return 10
        }
        if (fn() != 5) throw "early return failed"
    },

    test_function_no_return: function() {
        var fn = function() { var x = 5 }
        if (fn() != null) throw "function with no return should return null"
    },

    test_nested_function_calls: function() {
        var add = function(a, b) { return a + b }
        var mul = function(a, b) { return a * b }
        if (add(mul(2, 3), mul(4, 5)) != 26) throw "nested function calls failed"
    },

    test_function_as_value: function() {
        var fn = function() { return 42 }
        var fn2 = fn
        if (fn2() != 42) throw "function as value failed"
    },

    test_function_closure: function() {
        var outer = function(x) {
            return function(y) {
                return x + y
            }
        }
        var add5 = outer(5)
        if (add5(3) != 8) throw "closure failed"
    },

    test_function_closure_mutation: function() {
        var counter = function() {
            var count = 0
            return function() {
                count = count + 1
                return count
            }
        }
        var c = counter()
        if (c() != 1) throw "closure mutation failed (1)"
        if (c() != 2) throw "closure mutation failed (2)"
        if (c() != 3) throw "closure mutation failed (3)"
    },

    // ============================================================================
    // RECURSION
    // ============================================================================

    test_simple_recursion: function() {
        var factorial = function(n) {
            if (n <= 1) return 1
            return n * factorial(n - 1)
        }
        if (factorial(5) != 120) throw "factorial recursion failed"
    },

    test_mutual_recursion: function() {
        var isEven = function(n) {
            if (n == 0) return true
            return isOdd(n - 1)
        }
        var isOdd = function(n) {
            if (n == 0) return false
            return isEven(n - 1)
        }
        if (!isEven(4)) throw "mutual recursion even failed"
        if (isOdd(4)) throw "mutual recursion odd failed"
    },

    test_deep_recursion: function() {
        var sum = function(n) {
            if (n == 0) return 0
            return n + sum(n - 1)
        }
        if (sum(100) != 5050) throw "deep recursion failed"
    },

    // ============================================================================
    // ARRAYS
    // ============================================================================

    test_array_literal: function() {
        var arr = [1, 2, 3]
        if (arr[0] != 1 || arr[1] != 2 || arr[2] != 3) throw "array literal failed"
    },

    test_array_length: function() {
        var arr = [1, 2, 3, 4, 5]
        if (length(arr) != 5) throw "array length failed"
    },

    test_array_empty: function() {
        var arr = []
        if (length(arr) != 0) throw "empty array length failed"
    },

    test_array_push: function() {
        var arr = [1, 2]
        arr.push(3)
        if (length(arr) != 3) throw "array push length failed"
        if (arr[2] != 3) throw "array push value failed"
    },

    test_array_pop: function() {
        var arr = [1, 2, 3]
        var val = arr.pop()
        if (val != 3) throw "array pop value failed"
        if (length(arr) != 2) throw "array pop length failed"
    },

    test_array_index_access: function() {
        var arr = [10, 20, 30]
        if (arr[0] != 10) throw "array index 0 failed"
        if (arr[1] != 20) throw "array index 1 failed"
        if (arr[2] != 30) throw "array index 2 failed"
    },

    test_array_index_assignment: function() {
        var arr = [1, 2, 3]
        arr[1] = 99
        if (arr[1] != 99) throw "array index assignment failed"
    },

    test_array_mixed_types: function() {
        var arr = [1, "hello", true, null, {}]
        if (arr[0] != 1) throw "mixed array number failed"
        if (arr[1] != "hello") throw "mixed array string failed"
        if (arr[2] != true) throw "mixed array boolean failed"
        if (arr[3] != null) throw "mixed array null failed"
    },

    test_array_nested: function() {
        var arr = [[1, 2], [3, 4]]
        if (arr[0][0] != 1) throw "nested array access failed"
        if (arr[1][1] != 4) throw "nested array access failed"
    },

    // ============================================================================
    // OBJECTS
    // ============================================================================

    test_object_literal: function() {
        var obj = {a: 1, b: 2}
        if (obj.a != 1 || obj.b != 2) throw "object literal failed"
    },

    test_object_property_access: function() {
        var obj = {name: "Alice", age: 30}
        if (obj.name != "Alice") throw "object property access failed"
        if (obj.age != 30) throw "object property access failed"
    },

    test_object_bracket_access: function() {
        var obj = {x: 10, y: 20}
        if (obj["x"] != 10) throw "object bracket access failed"
        if (obj["y"] != 20) throw "object bracket access failed"
    },

    test_object_property_assignment: function() {
        var obj = {a: 1}
        obj.a = 99
        if (obj.a != 99) throw "object property assignment failed"
    },

    test_object_add_property: function() {
        var obj = {}
        obj.newProp = 42
        if (obj.newProp != 42) throw "object add property failed"
    },

    test_object_computed_property: function() {
        var key = "dynamicKey"
        var obj = {}
        obj[key] = 123
        if (obj.dynamicKey != 123) throw "object computed property failed"
    },

    test_object_nested: function() {
        var obj = {outer: {inner: 42}}
        if (obj.outer.inner != 42) throw "nested object access failed"
    },

    test_object_method: function() {
        var obj = {
            value: 10,
            getValue: function() { return this.value }
        }
        if (obj.getValue() != 10) throw "object method failed"
    },

    test_object_this_binding: function() {
        var obj = {
            x: 5,
            getX: function() { return this.x }
        }
        if (obj.getX() != 5) throw "this binding failed"
    },

    // ============================================================================
    // CONTROL FLOW - IF/ELSE
    // ============================================================================

    test_if_true: function() {
        var x = 0
        if (true) x = 1
        if (x != 1) throw "if true failed"
    },

    test_if_false: function() {
        var x = 0
        if (false) x = 1
        if (x != 0) throw "if false failed"
    },

    test_if_else_true: function() {
        var x = 0
        if (true) x = 1
        else x = 2
        if (x != 1) throw "if else true failed"
    },

    test_if_else_false: function() {
        var x = 0
        if (false) x = 1
        else x = 2
        if (x != 2) throw "if else false failed"
    },

    test_if_else_if: function() {
        var x = 0
        if (false) x = 1
        else if (true) x = 2
        else x = 3
        if (x != 2) throw "if else if failed"
    },

    test_nested_if: function() {
        var x = 0
        if (true) {
            if (true) {
                x = 1
            }
        }
        if (x != 1) throw "nested if failed"
    },

    // ============================================================================
    // CONTROL FLOW - WHILE LOOPS
    // ============================================================================

    test_while_loop: function() {
        var i = 0
        var sum = 0
        while (i < 5) {
            sum = sum + i
            i = i + 1
        }
        if (sum != 10) throw "while loop failed"
    },

    test_while_never_executes: function() {
        var x = 0
        while (false) {
            x = 1
        }
        if (x != 0) throw "while never executes failed"
    },

    test_while_break: function() {
        var i = 0
        while (true) {
            if (i >= 5) break
            i = i + 1
        }
        if (i != 5) throw "while break failed"
    },

    test_while_continue: function() {
        var i = 0
        var sum = 0
        while (i < 10) {
            i = i + 1
            if (i % 2 == 0) continue
            sum = sum + i
        }
        if (sum != 25) throw "while continue failed"
    },

    // ============================================================================
    // CONTROL FLOW - FOR LOOPS
    // ============================================================================

    test_for_loop: function() {
        var sum = 0
        for (var i = 0; i < 5; i = i + 1) {
            sum = sum + i
        }
        if (sum != 10) throw "for loop failed"
    },

    test_for_loop_break: function() {
        var sum = 0
        for (var i = 0; i < 10; i = i + 1) {
            if (i == 5) break
            sum = sum + i
        }
        if (sum != 10) throw "for loop break failed"
    },

    test_for_loop_continue: function() {
        var sum = 0
        for (var i = 0; i < 10; i = i + 1) {
            if (i % 2 == 0) continue
            sum = sum + i
        }
        if (sum != 25) throw "for loop continue failed"
    },

    test_for_in_array: function() {
        var arr = [10, 20, 30]
        var sum = 0
        for (var i in arr) {
            sum = sum + arr[i]
        }
        if (sum != 60) throw "for in array failed"
    },

    test_for_in_object: function() {
        var obj = {a: 1, b: 2, c: 3}
        var sum = 0
        for (var key in obj) {
            sum = sum + obj[key]
        }
        if (sum != 6) throw "for in object failed"
    },

    test_nested_for_loops: function() {
        var sum = 0
        for (var i = 0; i < 3; i = i + 1) {
            for (var j = 0; j < 3; j = j + 1) {
                sum = sum + 1
            }
        }
        if (sum != 9) throw "nested for loops failed"
    },

    // ============================================================================
    // CONTROL FLOW - SWITCH
    // ============================================================================

    test_switch_case: function() {
        var x = 2
        var result = 0
        switch (x) {
            case 1:
                result = 10
                break
            case 2:
                result = 20
                break
            case 3:
                result = 30
                break
        }
        if (result != 20) throw "switch case failed"
    },

    test_switch_default: function() {
        var x = 99
        var result = 0
        switch (x) {
            case 1:
                result = 10
                break
            default:
                result = -1
                break
        }
        if (result != -1) throw "switch default failed"
    },

    test_switch_fallthrough: function() {
        var x = 1
        var result = 0
        switch (x) {
            case 1:
                result = result + 1
            case 2:
                result = result + 2
                break
            case 3:
                result = result + 3
                break
        }
        if (result != 3) throw "switch fallthrough failed"
    },

    // ============================================================================
    // ERROR HANDLING - TRY/CATCH
    // ============================================================================

    test_try_catch: function() {
        var caught = false
        try {
            throw "error"
        } catch (e) {
            caught = true
        }
        if (!caught) throw "try catch failed"
    },

    test_try_catch_error_value: function() {
        var errorMsg = null
        try {
            throw "my error"
        } catch (e) {
            errorMsg = e
        }
        if (errorMsg != "my error") throw "try catch error value failed"
    },

    test_try_no_error: function() {
        var x = 0
        try {
            x = 1
        } catch (e) {
            x = 2
        }
        if (x != 1) throw "try no error failed"
    },

    test_nested_try_catch: function() {
        var x = 0
        try {
            try {
                throw "inner"
            } catch (e) {
                x = 1
            }
            x = 2
        } catch (e) {
            x = 3
        }
        if (x != 2) throw "nested try catch failed"
    },

    test_try_catch_rethrow: function() {
        var outerCaught = false
        try {
            try {
                throw "error"
            } catch (e) {
                throw e
            }
        } catch (e) {
            outerCaught = true
        }
        if (!outerCaught) throw "try catch rethrow failed"
    },

    // ============================================================================
    // TYPE CHECKING WITH is_* FUNCTIONS
    // ============================================================================

    test_is_number: function() {
        if (!is_number(42)) throw "is_number 42 failed"
        if (!is_number(3.14)) throw "is_number float failed"
        if (!is_number(-5)) throw "is_number negative failed"
        if (is_number("42")) throw "is_number string should be false"
        if (is_number(true)) throw "is_number boolean should be false"
        if (is_number(null)) throw "is_number null should be false"
        if (is_number({})) throw "is_number object should be false"
        if (is_number([])) throw "is_number array should be false"
    },

    test_is_text: function() {
        if (!is_text("hello")) throw "is_text string failed"
        if (!is_text("")) throw "is_text empty string failed"
        if (is_text(42)) throw "is_text number should be false"
        if (is_text(true)) throw "is_text boolean should be false"
        if (is_text(null)) throw "is_text null should be false"
        if (is_text({})) throw "is_text object should be false"
        if (is_text([])) throw "is_text array should be false"
    },

    test_is_logical: function() {
        if (!is_logical(true)) throw "is_logical true failed"
        if (!is_logical(false)) throw "is_logical false failed"
        if (is_logical(1)) throw "is_logical number should be false"
        if (is_logical("true")) throw "is_logical string should be false"
        if (is_logical(null)) throw "is_logical null should be false"
        if (is_logical({})) throw "is_logical object should be false"
        if (is_logical([])) throw "is_logical array should be false"
    },

    test_is_object: function() {
        if (!is_object({})) throw "is_object empty object failed"
        if (!is_object({a: 1})) throw "is_object object failed"
        if (is_object([])) throw "is_object array should be false"
        if (is_object(null)) throw "is_object null should be false"
        if (is_object(42)) throw "is_object number should be false"
        if (is_object("hello")) throw "is_object string should be false"
        if (is_object(true)) throw "is_object boolean should be false"
    },

    test_is_array: function() {
        if (!is_array([])) throw "is_array empty array failed"
        if (!is_array([1, 2, 3])) throw "is_array array failed"
        if (is_array({})) throw "is_array object should be false"
        if (is_array(null)) throw "is_array null should be false"
        if (is_array(42)) throw "is_array number should be false"
        if (is_array("hello")) throw "is_array string should be false"
        if (is_array(true)) throw "is_array boolean should be false"
    },

    test_is_function: function() {
        if (!is_function(function(){})) throw "is_function function failed"
        var fn = function(x) { return x * 2 }
        if (!is_function(fn)) throw "is_function named function failed"
        if (is_function({})) throw "is_function object should be false"
        if (is_function([])) throw "is_function array should be false"
        if (is_function(null)) throw "is_function null should be false"
        if (is_function(42)) throw "is_function number should be false"
        if (is_function("hello")) throw "is_function string should be false"
        if (is_function(true)) throw "is_function boolean should be false"
    },

    test_is_null: function() {
        if (!is_null(null)) throw "is_null null failed"
        if (is_null(0)) throw "is_null zero should be false"
        if (is_null(false)) throw "is_null false should be false"
        if (is_null("")) throw "is_null empty string should be false"
        if (is_null({})) throw "is_null object should be false"
        if (is_null([])) throw "is_null array should be false"
        var x
        if (!is_null(x)) throw "is_null undefined variable should be true"
    },

    test_is_blob: function() {
        // Note: blob testing would require actual blob values
        // For now, just test that other types return false
        if (is_blob(null)) throw "is_blob null should be false"
        if (is_blob(42)) throw "is_blob number should be false"
        if (is_blob("hello")) throw "is_blob string should be false"
        if (is_blob(true)) throw "is_blob boolean should be false"
        if (is_blob({})) throw "is_blob object should be false"
        if (is_blob([])) throw "is_blob array should be false"
        if (is_blob(function(){})) throw "is_blob function should be false"
    },

    // ============================================================================
    // ISA TYPE CHECKING
    // ============================================================================

    test_isa_number: function() {
        if (!is_number(42)) throw "isa number failed"
        if (is_number("42")) throw "isa string not number failed"
    },

    test_isa_text: function() {
        if (!is_text("hello")) throw "isa text failed"
        if (is_text(123)) throw "isa number not text failed"
    },

    test_isa_logical: function() {
        if (!is_logical(true)) throw "isa true failed"
        if (!is_logical(false)) throw "isa false failed"
        if (is_logical(1)) throw "isa number not logical failed"
    },

    test_isa_array: function() {
        if (!is_array([], array)) throw "isa empty array failed"
        if (!is_array([1,2,3], array)) throw "isa array failed"
        if (is_array({}, array)) throw "isa object not array failed"
    },

    test_isa_object: function() {
        if (!is_object({}, object)) throw "isa empty object failed"
        if (!is_object({a:1}, object)) throw "isa object failed"
        if (is_object([], object)) throw "isa array not object failed"
        if (is_object(null, object)) throw "isa null not object failed"
    },

    test_isa_null: function() {
        if (is_null(null)) throw "null not number"
        if (is_null(text)) throw "null not text"
        if (is_null(object)) throw "null not object"
    },

    test_is_proto: function() {
        var a = {}
        var b = meme(a)
        if (!is_proto(b, a)) throw "is_proto failed on meme"

        var c = Error()
        if (!is_proto(c, Error)) throw "is_proto failed new"
    },

    // ============================================================================
    // GLOBAL FUNCTIONS - LENGTH
    // ============================================================================

    test_length_string: function() {
        if (length("hello") != 5) throw "length string failed"
        if (length("") != 0) throw "length empty string failed"
    },

    test_length_array: function() {
        if (length([1,2,3]) != 3) throw "length array failed"
        if (length([]) != 0) throw "length empty array failed"
    },

    test_length_null: function() {
        if (length(null) != null) throw "length null failed"
    },

    test_length_number: function() {
        if (length(123) != null) throw "length number should return null"
    },

    // ============================================================================
    // GLOBAL FUNCTIONS - REVERSE
    // ============================================================================

    test_reverse_array: function() {
        var arr = [1, 2, 3, 4, 5]
        var rev = reverse(arr)
        if (rev[0] != 5) throw "reverse array first failed"
        if (rev[4] != 1) throw "reverse array last failed"
        if (length(rev) != 5) throw "reverse array length failed"
    },

    test_reverse_empty_array: function() {
        var rev = reverse([])
        if (length(rev) != 0) throw "reverse empty array failed"
    },

    test_reverse_preserves_original: function() {
        var arr = [1, 2, 3]
        var rev = reverse(arr)
        if (arr[0] != 1) throw "reverse should not mutate original"
    },

    // ============================================================================
    // GLOBAL FUNCTIONS - MEME (PROTOTYPAL INHERITANCE)
    // ============================================================================

    test_meme_basic: function() {
        var parent = {x: 10}
        var child = meme(parent)
        if (child.x != 10) throw "meme basic inheritance failed"
    },

    test_meme_with_mixins: function() {
        var parent = {x: 10}
        var mixin = {y: 20}
        var child = meme(parent, mixin)
        if (child.x != 10) throw "meme with mixin parent prop failed"
        if (child.y != 20) throw "meme with mixin own prop failed"
    },

    test_meme_override: function() {
        var parent = {x: 10}
        var child = meme(parent)
        child.x = 20
        if (child.x != 20) throw "meme override failed"
        if (parent.x != 10) throw "meme should not mutate parent"
    },

    test_meme_multiple_mixins: function() {
        var parent = {a: 1}
        var mixin1 = {b: 2}
        var mixin2 = {c: 3}
        var child = meme(parent, mixin1, mixin2)
        if (child.a != 1 || child.b != 2 || child.c != 3) throw "meme multiple mixins failed"
    },

    // ============================================================================
    // GLOBAL FUNCTIONS - PROTO
    // ============================================================================

    test_proto_basic: function() {
        var parent = {x: 10}
        var child = meme(parent)
        var p = proto(child)
        if (p != parent) throw "proto basic failed"
    },

    test_proto_object_literal: function() {
        var obj = {x: 10}
        var p = proto(obj)
        if (p != null) throw "proto of object literal should be null"
    },

    test_proto_non_object: function() {
        if (proto(42) != null) throw "proto of number should return null"
        if (proto("hello") != null) throw "proto of string should return null"
    },

    // ============================================================================
    // GLOBAL FUNCTIONS - STONE (FREEZE)
    // ============================================================================

    test_stone_object: function() {
        var obj = {x: 10}
        stone(obj)
        var caught = false
        try {
            obj.x = 20
        } catch (e) {
            caught = true
        }
        if (!caught) throw "stone object should prevent modification"
    },

    test_stone_p_frozen: function() {
        var obj = {x: 10}
        if (stone.p(obj)) throw "stone.p should return false before freezing"
        stone(obj)
        if (!stone.p(obj)) throw "stone.p should return true after freezing"
    },

    test_stone_array: function() {
        var arr = [1, 2, 3]
        stone(arr)
        var caught = false
        try {
            arr[0] = 99
        } catch (e) {
            caught = true
        }
        if (!caught) throw "stone array should prevent modification"
    },

    // ============================================================================
    // TERNARY OPERATOR
    // ============================================================================

    test_ternary_true: function() {
        var x = true ? 1 : 2
        if (x != 1) throw "ternary true failed"
    },

    test_ternary_false: function() {
        var x = false ? 1 : 2
        if (x != 2) throw "ternary false failed"
    },

    test_ternary_nested: function() {
        var x = true ? (false ? 1 : 2) : 3
        if (x != 2) throw "ternary nested failed"
    },

    test_ternary_with_expressions: function() {
        var a = 5
        var b = 10
        var max = (a > b) ? a : b
        if (max != 10) throw "ternary with expressions failed"
    },

    // ============================================================================
    // UNARY OPERATORS
    // ============================================================================

    test_unary_plus: function() {
        if (+5 != 5) throw "unary plus positive failed"
        if (+-5 != -5) throw "unary plus negative failed"
    },

    test_unary_minus: function() {
        if (-5 != -5) throw "unary minus failed"
        if (-(-5) != 5) throw "double unary minus failed"
    },

    test_increment_postfix: function() {
        var x = 5
        var y = x++
        if (y != 5) throw "postfix increment return value failed"
        if (x != 6) throw "postfix increment side effect failed"
    },

    test_increment_prefix: function() {
        var x = 5
        var y = ++x
        if (y != 6) throw "prefix increment return value failed"
        if (x != 6) throw "prefix increment side effect failed"
    },

    test_decrement_postfix: function() {
        var x = 5
        var y = x--
        if (y != 5) throw "postfix decrement return value failed"
        if (x != 4) throw "postfix decrement side effect failed"
    },

    test_decrement_prefix: function() {
        var x = 5
        var y = --x
        if (y != 4) throw "prefix decrement return value failed"
        if (x != 4) throw "prefix decrement side effect failed"
    },

    // ============================================================================
    // COMPOUND ASSIGNMENT OPERATORS
    // ============================================================================

    test_plus_equals: function() {
        var x = 5
        x += 3
        if (x != 8) throw "plus equals failed"
    },

    test_minus_equals: function() {
        var x = 10
        x -= 3
        if (x != 7) throw "minus equals failed"
    },

    test_times_equals: function() {
        var x = 4
        x *= 3
        if (x != 12) throw "times equals failed"
    },

    test_divide_equals: function() {
        var x = 12
        x /= 3
        if (x != 4) throw "divide equals failed"
    },

    test_modulo_equals: function() {
        var x = 10
        x %= 3
        if (x != 1) throw "modulo equals failed"
    },

    // ============================================================================
    // EDGE CASES AND SPECIAL VALUES
    // ============================================================================

    test_infinity: function() {
        var inf = 1 / 0
        if (!(inf > 1000000)) throw "infinity failed"
        if (!(-inf < -1000000)) throw "negative infinity failed"
    },

    test_nan: function() {
        var nan = 0 / 0
        if (nan == nan) throw "NaN should not equal itself"
    },

    test_max_safe_integer: function() {
        var max = 9007199254740991
        if (max + 1 - 1 != max) throw "max safe integer precision lost"
    },

    test_min_safe_integer: function() {
        var min = -9007199254740991
        if (min - 1 + 1 != min) throw "min safe integer precision lost"
    },

    test_empty_string_falsy: function() {
        if ("") throw "empty string should be falsy"
    },

    test_zero_falsy: function() {
        if (0) throw "zero should be falsy"
    },

    test_null_falsy: function() {
        if (null) throw "null should be falsy"
    },

    test_false_falsy: function() {
        if (false) throw "false should be falsy"
    },

    test_nonempty_string_truthy: function() {
        if (!"hello") throw "non-empty string should be truthy"
    },

    test_nonzero_number_truthy: function() {
        if (!42) throw "non-zero number should be truthy"
    },

    test_object_truthy: function() {
        if (!{}) throw "empty object should be truthy"
    },

    test_array_truthy: function() {
        if (![]) throw "empty array should be truthy"
    },

    // ============================================================================
    // OPERATOR PRECEDENCE
    // ============================================================================

    test_precedence_multiply_add: function() {
        if (2 + 3 * 4 != 14) throw "multiply before add precedence failed"
    },

    test_precedence_parentheses: function() {
        if ((2 + 3) * 4 != 20) throw "parentheses precedence failed"
    },

    test_precedence_comparison_logical: function() {
        if (!(1 < 2 && 3 < 4)) throw "comparison before logical precedence failed"
    },

    test_precedence_equality_logical: function() {
        if (!(1 == 1 || 2 == 3)) throw "equality before logical precedence failed"
    },

    test_precedence_unary_multiplication: function() {
        if (-2 * 3 != -6) throw "unary before multiplication precedence failed"
    },

    // ============================================================================
    // COMMA OPERATOR
    // ============================================================================

    test_comma_operator: function() {
        var x = (1, 2, 3)
        if (x != 3) throw "comma operator failed"
    },

    test_comma_operator_with_side_effects: function() {
        var a = 0
        var x = (a = 1, a = 2, a + 1)
        if (x != 3) throw "comma operator with side effects failed"
        if (a != 2) throw "comma operator side effects failed"
    },

    // ============================================================================
    // VARIABLE SHADOWING
    // ============================================================================

    test_variable_shadowing_function: function() {
        var x = 10
        var fn = function() {
            var x = 20
            return x
        }
        if (fn() != 20) throw "function shadowing failed"
        if (x != 10) throw "outer variable after shadowing failed"
    },

    test_variable_shadowing_nested: function() {
        var x = 10
        var fn1 = function() {
            var x = 20
            var fn2 = function() {
                var x = 30
                return x
            }
            return fn2() + x
        }
        if (fn1() != 50) throw "nested shadowing failed"
    },

    // ============================================================================
    // FUNCTION ARITY
    // ============================================================================

    test_function_length_property: function() {
        var fn0 = function() {}
        var fn1 = function(a) {}
        var fn2 = function(a, b) {}
        if (length(fn0) != 0) throw "function length 0 failed"
        if (length(fn1) != 1) throw "function length 1 failed"
        if (length(fn2) != 2) throw "function length 2 failed"
    },

    // ============================================================================
    // NULL AND UNDEFINED BEHAVIOR
    // ============================================================================

    test_undefined_variable_is_null: function() {
        var x
        if (x != null) throw "undefined variable should be null"
    },

    // ============================================================================
    // NUMBERS - SPECIAL OPERATIONS
    // ============================================================================

    test_number_toString_implicit: function() {
        var n = 42
        var caught = false
        try {
            var result = n + ""
        } catch (e) {
            caught = true
        }
        if (!caught) throw "number + string should throw"
    },

    test_number_division_by_zero: function() {
        var result = 1 / 0
        if (!(result > 1000000)) throw "division by zero should give infinity"
    },

    test_number_negative_division_by_zero: function() {
        var result = -1 / 0
        if (!(result < -1000000)) throw "negative division by zero should give -infinity"
    },

    test_zero_division_by_zero: function() {
        var result = 0 / 0
        if (result == result) throw "0/0 should give NaN"
    },

    // ============================================================================
    // OBJECT PROPERTY EXISTENCE
    // ============================================================================

    test_in_operator: function() {
        var obj = {a: 1, b: 2}
        if (!("a" in obj)) throw "in operator for existing property failed"
        if ("c" in obj) throw "in operator for non-existing property failed"
    },

    test_in_operator_array: function() {
        var arr = [10, 20, 30]
        if (!(0 in arr)) throw "in operator for array index 0 failed"
        if (!(2 in arr)) throw "in operator for array index 2 failed"
        if (3 in arr) throw "in operator for out of bounds index failed"
    },

    test_in_operator_prototype: function() {
        var parent = {x: 10}
        var child = meme(parent)
        if (!("x" in child)) throw "in operator should find inherited property"
    },

    // ============================================================================
    // GLOBAL FUNCTIONS - LOGICAL
    // ============================================================================

    test_logical_function_numbers: function() {
        if (logical(0) != false) throw "logical(0) should be false"
        if (logical(1) != true) throw "logical(1) should be true"
    },

    test_logical_function_strings: function() {
        if (logical("false") != false) throw "logical('false') should be false"
        if (logical("true") != true) throw "logical('true') should be true"
    },

    test_logical_function_booleans: function() {
        if (logical(false) != false) throw "logical(false) should be false"
        if (logical(true) != true) throw "logical(true) should be true"
    },

    test_logical_function_null: function() {
        if (logical(null) != false) throw "logical(null) should be false"
    },

    test_logical_function_invalid: function() {
        if (logical("invalid") != null) throw "logical(invalid) should return null"
        if (logical(42) != null) throw "logical(42) should return null"
    },

    // ============================================================================
    // ARRAY METHODS
    // ============================================================================

    test_array_shift: function() {
        var arr = [1, 2, 3]
        var first = arr.shift()
        if (first != 1) throw "array shift value failed"
        if (length(arr) != 2) throw "array shift length failed"
        if (arr[0] != 2) throw "array shift remaining failed"
    },

    test_array_unshift: function() {
        var arr = [2, 3]
        arr.unshift(1)
        if (length(arr) != 3) throw "array unshift length failed"
        if (arr[0] != 1) throw "array unshift value failed"
    },

    test_array_splice: function() {
        var arr = [1, 2, 3, 4, 5]
        var removed = arr.splice(1, 2)
        if (length(removed) != 2) throw "array splice removed length failed"
        if (removed[0] != 2) throw "array splice removed values failed"
        if (length(arr) != 3) throw "array splice remaining length failed"
        if (arr[1] != 4) throw "array splice remaining values failed"
    },

    test_array_slice: function() {
        var arr = [1, 2, 3, 4, 5]
        var sliced = arr.slice(1, 3)
        if (length(sliced) != 2) throw "array slice length failed"
        if (sliced[0] != 2) throw "array slice first failed"
        if (sliced[1] != 3) throw "array slice second failed"
        if (length(arr) != 5) throw "array slice should not mutate original"
    },

    test_array_concat: function() {
        var arr1 = [1, 2]
        var arr2 = [3, 4]
        var combined = arr1.concat(arr2)
        if (length(combined) != 4) throw "array concat length failed"
        if (combined[2] != 3) throw "array concat values failed"
    },

    test_array_join: function() {
        var arr = [1, 2, 3]
        var caught = false
        try {
            var str = arr.join(",")
        } catch (e) {
            caught = true
        }
    },

    test_array_indexOf: function() {
        var arr = [10, 20, 30, 20]
        if (arr.indexOf(20) != 1) throw "array indexOf failed"
        if (arr.indexOf(99) != -1) throw "array indexOf not found failed"
    },

    test_array_lastIndexOf: function() {
        var arr = [10, 20, 30, 20]
        if (arr.lastIndexOf(20) != 3) throw "array lastIndexOf failed"
        if (arr.lastIndexOf(99) != -1) throw "array lastIndexOf not found failed"
    },

    // ============================================================================
    // STRING METHODS
    // ============================================================================

    test_string_charAt: function() {
        var str = "hello"
        if (str.charAt(0) != "h") throw "string charAt first failed"
        if (str.charAt(4) != "o") throw "string charAt last failed"
    },

    test_string_charCodeAt: function() {
        var str = "A"
        if (str.charCodeAt(0) != 65) throw "string charCodeAt failed"
    },

    test_string_substring: function() {
        var str = "hello"
        if (str.substring(1, 4) != "ell") throw "string substring failed"
    },

    test_string_substr: function() {
        var str = "hello"
        if (str.substr(1, 3) != "ell") throw "string substr failed"
    },

    test_string_slice: function() {
        var str = "hello"
        if (str.slice(1, 4) != "ell") throw "string slice failed"
        if (str.slice(-2) != "lo") throw "string slice negative failed"
    },

    test_string_indexOf: function() {
        var str = "hello world"
        if (str.indexOf("world") != 6) throw "string indexOf failed"
        if (str.indexOf("xyz") != -1) throw "string indexOf not found failed"
    },

    test_string_lastIndexOf: function() {
        var str = "hello hello"
        if (str.lastIndexOf("hello") != 6) throw "string lastIndexOf failed"
    },

    test_string_toLowerCase: function() {
        var str = "HELLO"
        if (str.toLowerCase() != "hello") throw "string toLowerCase failed"
    },

    test_string_toUpperCase: function() {
        var str = "hello"
        if (str.toUpperCase() != "HELLO") throw "string toUpperCase failed"
    },

    test_string_trim: function() {
        var str = "  hello  "
        if (str.trim() != "hello") throw "string trim failed"
    },

    test_string_split: function() {
        var str = "a,b,c"
        var parts = str.split(",")
        if (length(parts) != 3) throw "string split length failed"
        if (parts[1] != "b") throw "string split values failed"
    },

    test_string_replace: function() {
        var str = "hello world"
        var replaced = str.replace("world", "universe")
        if (replaced != "hello universe") throw "string replace failed"
    },

    test_string_match: function() {
        var str = "hello123"
        var hasNumbers = /\d/.test(str)
        if (!hasNumbers) throw "string match with regex failed"
    },

    test_string_plus_string_works: function() {
        var x = "hello" + " world"
        if (x != "hello world") throw "string + string should work"
    },

    null_access: function() {
        var val = {}
        var nn = val.a
        if (nn != null) throw "val.a should return null"
    },

    // ============================================================================
    // OBJECT-AS-KEY (Private Property Access)
    // ============================================================================

    test_object_key_basic: function() {
        var k1 = {}
        var k2 = {}
        var o = {}
        o[k1] = 123
        o[k2] = 456
        if (o[k1] != 123) throw "object key k1 failed"
        if (o[k2] != 456) throw "object key k2 failed"
    },

    test_object_key_new_object_different_key: function() {
        var k1 = {}
        var o = {}
        o[k1] = 123
        if (o[{}] != null) throw "new object should be different key"
    },

    test_object_key_in_operator: function() {
        var k1 = {}
        var o = {}
        o[k1] = 123
        if (!(k1 in o)) throw "in operator should find object key"
    },

    test_object_key_delete: function() {
        var k1 = {}
        var o = {}
        o[k1] = 123
        delete o[k1]
        if ((k1 in o)) throw "delete should remove object key"
    },

    test_object_key_no_string_collision: function() {
        var a = {}
        var b = {}
        var o = {}
        o[a] = 1
        o[b] = 2
        if (o[a] != 1) throw "object key a should be 1"
        if (o[b] != 2) throw "object key b should be 2"
    },

    test_object_key_same_object_same_key: function() {
        var k = {}
        var o = {}
        o[k] = 100
        o[k] = 200
        if (o[k] != 200) throw "same object should be same key"
    },

    test_object_key_not_in_for_in: function() {
        var k = {}
        var o = {a: 1, b: 2}
        o[k] = 999
        var count = 0
        for (var key in o) {
            count = count + 1
            if (key == k) throw "object key should not appear in for-in"
        }
        if (count != 2) throw "for-in should only see string keys"
    },

    test_object_key_computed_property: function() {
        var k = {}
        var o = {}
        o[k] = function() { return 42 }
        if (o[k]() != 42) throw "object key with function value failed"
    },

    test_object_key_multiple_objects_multiple_keys: function() {
        var k1 = {}
        var k2 = {}
        var k3 = {}
        var o = {}
        o[k1] = "one"
        o[k2] = "two"
        o[k3] = "three"
        if (o[k1] != "one") throw "multiple keys k1 failed"
        if (o[k2] != "two") throw "multiple keys k2 failed"
        if (o[k3] != "three") throw "multiple keys k3 failed"
    },

    test_object_key_with_string_keys: function() {
        var k = {}
        var o = {name: "test"}
        o[k] = "private"
        if (o.name != "test") throw "string key should still work"
        if (o[k] != "private") throw "object key should work with string keys"
    },

    test_object_key_overwrite: function() {
        var k = {}
        var o = {}
        o[k] = 1
        o[k] = 2
        o[k] = 3
        if (o[k] != 3) throw "object key overwrite failed"
    },

    test_object_key_nested_objects: function() {
        var k1 = {}
        var k2 = {}
        var inner = {}
        inner[k2] = "nested"
        var outer = {}
        outer[k1] = inner
        if (outer[k1][k2] != "nested") throw "nested object keys failed"
    },

    test_array_number_key: function() {
        var a = []
        a[1] = 1
        if (a[1] != 1) throw "array should be able to use number as key"
    },

    test_array_string_key_throws: function() {
        var a = []
        var caught = false
        try {
            a["a"] = 1
        } catch(e) {
            caught = true
        }
        if (!caught) throw "array should not be able to use string as key"
    },

    test_array_object_key_throws: function() {
        var a = []
        var b = {}
        var caught = false
        try {
            a[b] = 1
        } catch(e) {
            caught = true
        }
        if (!caught) throw "array should not be able to use object as key"
    },

    test_array_boolean_key_throws: function() {
        var a = []
        var caught = false
        try {
            a[true] = 1
        } catch(e) {
            caught = true
        }
        if (!caught) throw "array should not be able to use boolean as key"
    },

    test_array_null_key_throws: function() {
        var a = []
        var caught = false
        try {
            a[null] = 1
        } catch(e) {
            caught = true
        }
        if (!caught) throw "array should not be able to use null as key"
    },

    test_array_array_key_throws: function() {
        var a = []
        var c = []
        var caught = false
        try {
            a[c] = 1
        } catch(e) {
            caught = true
        }
        if (!caught) throw "array should not be able to use array as key"
    },

    test_obj_number_key_throws: function() {
        var a = {}
        var caught = false
        try {
            a[1] = 1
        } catch(e) {
            caught = true
        }
        if (!caught) throw "object should not be able to use number as key"
    },

    test_obj_array_key_throws: function() {
        var a = {}
        var c = []
        var caught = false
        try {
            a[c] = 1
        } catch(e) {
            caught = true
        }
        if (!caught) throw "object should not be able to use array as key"
    },

    test_obj_boolean_key_throws: function() {
        var a = {}
        var caught = false
        try {
            a[true] = 1
        } catch(e) {
            caught = true
        }
        if (!caught) throw "object should not be able to use boolean as key"
    },

    test_obj_null_key_throws: function() {
        var a = {}
        var caught = false
        try {
            a[null] = 1
        } catch(e) {
            caught = true
        }
        if (!caught) throw "object should not be able to use null as key"
    },

    // ============================================================================
    // RETRIEVAL WITH INVALID KEY RETURNS NULL (not throw)
    // ============================================================================

    test_array_get_string_key_returns_null: function() {
        var a = [1, 2, 3]
        var result = a["x"]
        if (result != null) throw "array get with string key should return null"
    },

    test_array_get_negative_index_returns_null: function() {
        var a = [1, 2, 3]
        var result = a[-1]
        if (result != null) throw "array get with negative index should return null"
    },

    test_array_get_object_key_returns_null: function() {
        var a = [1, 2, 3]
        var k = {}
        var result = a[k]
        if (result != null) throw "array get with object key should return null"
    },

    test_array_get_array_key_returns_null: function() {
        var a = [1, 2, 3]
        var result = a[[1, 2]]
        if (result != null) throw "array get with array key should return null"
    },

    test_array_get_boolean_key_returns_null: function() {
        var a = [1, 2, 3]
        var result = a[true]
        if (result != null) throw "array get with boolean key should return null"
    },

    test_array_get_null_key_returns_null: function() {
        var a = [1, 2, 3]
        var result = a[null]
        if (result != null) throw "array get with null key should return null"
    },

    test_obj_get_number_key_returns_null: function() {
        var o = {a: 1}
        var result = o[5]
        if (result != null) throw "object get with number key should return null"
    },

    test_obj_get_array_key_returns_null: function() {
        var o = {a: 1}
        var result = o[[1, 2]]
        if (result != null) throw "object get with array key should return null"
    },

    test_obj_get_boolean_key_returns_null: function() {
        var o = {a: 1}
        var result = o[true]
        if (result != null) throw "object get with boolean key should return null"
    },

    test_obj_get_null_key_returns_null: function() {
        var o = {a: 1}
        var result = o[null]
        if (result != null) throw "object get with null key should return null"
    },

    // ============================================================================
    // FUNCTION AS VALUE (not object) - functions should not have properties
    // ============================================================================

    test_function_property_get_throws: function() {
        var fn = function(a, b) { return a + b }
        var caught = false
        try {
            var x = fn.length
        } catch (e) {
            caught = true
        }
        if (!caught) throw "getting property on function should throw"
    },

    test_function_property_set_throws: function() {
        var fn = function() {}
        var caught = false
        try {
            fn.foo = 123
        } catch (e) {
            caught = true
        }
        if (!caught) throw "setting property on function should throw"
    },

    test_function_bracket_access_throws: function() {
        var fn = function() {}
        var caught = false
        try {
            var x = fn["length"]
        } catch (e) {
            caught = true
        }
        if (!caught) throw "bracket access on function should throw"
    },

    test_length_returns_function_arity: function() {
        var fn0 = function() { return 1 }
        var fn1 = function(a) { return a }
        var fn2 = function(a, b) { return a + b }
        var fn3 = function(a, b, c) { return a + b + c }

        if (length(fn0) != 0) throw "length(fn0) should be 0"
        if (length(fn1) != 1) throw "length(fn1) should be 1"
        if (length(fn2) != 2) throw "length(fn2) should be 2"
        if (length(fn3) != 3) throw "length(fn3) should be 3"
    },

    test_text_returns_function_source: function() {
        var fn = function(x) { return x * 2 }
        var src = text(fn)
        if (src.indexOf("function") == -1) throw "text(fn) should contain 'function'"
        if (src.indexOf("return") == -1) throw "text(fn) should contain function body"
    },

    test_call_invokes_function: function() {
        var fn = function(a, b) { return a + b }
        var result = call(fn, null, 3, 4)
        if (result != 7) throw "call(fn, null, 3, 4) should return 7"
    },

    test_call_with_this_binding: function() {
        var obj = { value: 10 }
        var fn = function(x) { return this.value + x }
        var result = call(fn, obj, 5)
        if (result != 15) throw "call(fn, obj, 5) should return 15"
    },

    test_call_no_args: function() {
        var fn = function() { return 42 }
        var result = call(fn, null)
        if (result != 42) throw "call(fn, null) should return 42"
    },

    test_builtin_function_properties_still_work: function() {
        // Built-in functions like number, text, array should still have properties
        var min_result = number.min(5, 3)
        if (min_result != 3) throw "number.min should work"
    },

    // ============================================================================
    // FUNCTION PROXY - Method call sugar for bytecode functions
    // ============================================================================

    test_function_proxy_basic: function() {
        var proxy = function(name, args) {
            return `called:${name}:${length(args)}`
        }
        var result = proxy.foo()
        if (result != "called:foo:0") throw "basic proxy call failed"
    },

    test_function_proxy_with_one_arg: function() {
        var proxy = function(name, args) {
            return `${name}-${args[0]}`
        }
        var result = proxy.test("value")
        if (result != "test-value") throw "proxy with one arg failed"
    },

    test_function_proxy_with_multiple_args: function() {
        var proxy = function(name, args) {
            var sum = 0
            for (var i = 0; i < length(args); i++) {
                sum = sum + args[i]
            }
            return `${name}:${sum}`
        }
        var result = proxy.add(1, 2, 3, 4)
        if (result != "add:10") throw "proxy with multiple args failed"
    },

    test_function_proxy_bracket_notation: function() {
        var proxy = function(name, args) {
            return `bracket:${name}`
        }
        var result = proxy["myMethod"]()
        if (result != "bracket:myMethod") throw "proxy bracket notation failed"
    },

    test_function_proxy_dynamic_method_name: function() {
        var proxy = function(name, args) {
            return name
        }
        var methodName = "dynamic"
        var result = proxy[methodName]()
        if (result != "dynamic") throw "proxy dynamic method name failed"
    },

    test_function_proxy_dispatch_to_record: function() {
        var my_record = {
            greet: function(name) {
                return `Hello, ${name}`
            },
            add: function(a, b) {
                return a + b
            }
        }

        var proxy = function(name, args) {
            if (is_function(my_record[name])) {
                return fn.apply(my_record[name], args)
            }
            throw `unknown method: ${name}`
        }

        if (proxy.greet("World") != "Hello, World") throw "proxy dispatch greet failed"
        if (proxy.add(3, 4) != 7) throw "proxy dispatch add failed"
    },

    test_function_proxy_unknown_method_throws: function() {
        var proxy = function(name, args) {
            throw `no such method: ${name}`
        }
        var caught = false
        try {
            proxy.nonexistent()
        } catch (e) {
            caught = true
            if (e.indexOf("no such method") == -1) throw "wrong error message"
        }
        if (!caught) throw "proxy should throw for unknown method"
    },

    test_function_proxy_is_function: function() {
        var proxy = function(name, args) {
            return name
        }
        if (!is_function(proxy)) throw "proxy should be a function"
    },

    test_function_proxy_length_is_2: function() {
        var proxy = function(name, args) {
            return name
        }
        if (length(proxy) != 2) throw "proxy function should have length 2"
    },

    test_function_proxy_property_read_still_throws: function() {
        var fn = function() { return 1 }
        var caught = false
        try {
            var x = fn.someProp
        } catch (e) {
            caught = true
        }
        if (!caught) throw "reading property from function (not method call) should throw"
    },

    test_function_proxy_nested_calls: function() {
        var outer = function(name, args) {
            if (name == "inner") {
                return args[0].double(5)
            }
            return "outer:" + name
        }
        var inner = function(name, args) {
            if (name == "double") {
                return args[0] * 2
            }
            return "inner:" + name
        }
        var result = outer.inner(inner)
        if (result != 10) throw "nested proxy calls failed"
    },

    test_function_proxy_returns_null: function() {
        var proxy = function(name, args) {
            return null
        }
        var result = proxy.anything()
        if (result != null) throw "proxy returning null failed"
    },

    test_function_proxy_returns_object: function() {
        var proxy = function(name, args) {
            return {method: name, argCount: length(args)}
        }
        var result = proxy.test(1, 2, 3)
        if (result.method != "test") throw "proxy returning object method failed"
        if (result.argCount != 3) throw "proxy returning object argCount failed"
    },

    test_function_proxy_returns_function: function() {
        var proxy = function(name, args) {
            return function() { return name }
        }
        var result = proxy.getFn()
        if (result() != "getFn") throw "proxy returning function failed"
    },

    test_function_proxy_args_array_is_real_array: function() {
        var proxy = function(name, args) {
            if (!is_array(args)) throw "args should be array"
            args.push(4)
            return length(args)
        }
        var result = proxy.test(1, 2, 3)
        if (result != 4) throw "proxy args should be modifiable array"
    },

    test_function_proxy_no_this_binding: function() {
        var proxy = function(name, args) {
            return this
        }
        var result = proxy.test()
        if (result != null) throw "proxy should have null this"
    },

    test_function_proxy_integer_bracket_key: function() {
        var proxy = function(name, args) {
            return `key:${name}`
        }
        var result = proxy[42]()
        if (result != "key:42") throw "proxy with integer bracket key failed"
    },

}