OxideJS-New/crates/oxide_vm/tests/builtins_iterator_tests.rs

use oxide_compiler::compiler::Compiler;
use oxide_types::object::JsObject;
use oxide_types::value::JsValue;
use oxide_vm::vm::Vm;

fn eval(vm: &mut Vm, source: &str) -> Result<JsValue, String> {
    let allocator = oxide_parser::Allocator::default();
    let program = oxide_parser::parse(&allocator, source).map_err(|e| format!("Parse error: {:?}", e))?;
    let module = Compiler::new().compile(&program).map_err(|e| format!("Compile error: {}", e))?;
    vm.run(&module)
}

fn to_str(vm: &Vm, val: JsValue) -> String {
    vm.lookup_str(val).unwrap_or_default()
}

#[test]
fn iterator_global_exists() {
    let mut vm = Vm::new();
    let result = eval(&mut vm, "typeof Iterator").unwrap();
    assert_eq!(to_str(&vm, result), "function");
}

#[test]
fn iterator_from_array_returns_values_until_done() {
    let mut vm = Vm::new();
    let result = eval(
        &mut vm,
        "var iter = Iterator.from([1, 2, 3]); \
         var a = iter.next(); var b = iter.next(); var c = iter.next(); var d = iter.next(); \
         a.value === 1 && a.done === false && b.value === 2 && c.value === 3 && d.done === true",
    )
    .unwrap();
    assert!(result.as_bool());
}

#[test]
fn iterator_from_string_returns_chars() {
    let mut vm = Vm::new();
    let result = eval(&mut vm, "var iter = Iterator.from('abc'); iter.next().value").unwrap();
    assert_eq!(to_str(&vm, result), "a");
}

#[test]
fn iterator_from_iterator_forwards_next() {
    let mut vm = Vm::new();
    let result = eval(
        &mut vm,
        "var inner = { next: function() { return { value: 7, done: false }; } }; \
         Iterator.from(inner).next().value",
    )
    .unwrap();
    assert_eq!(result.as_int(), 7);
}

#[test]
fn iterator_from_duck_fallback_next_getter_read_only_once() {
    // 鸭子回退的 from() 恰读一次 next getter（规范单读语义）：
    // 包装器缓存 from() 时读到的闭包，消费期直用缓存闭包——getter 不被重触发，
    // 底层新产的值经同一闭包透出。
    let mut vm = Vm::new();
    let bool_cases = [
        (
            "var nextGets = 0; \
             var nextCalls = 0; \
             var obj = { \
               get next() { \
                 ++nextGets; \
                 var i = 0; \
                 return function () { \
                   ++nextCalls; \
                   return i < 4 ? { value: i++, done: false } : { value: undefined, done: true }; \
                 }; \
               }, \
             }; \
             var it = Iterator.from(obj); \
             nextGets === 1 && nextCalls === 0",
            true,
        ),
        (
            "var nextGets = 0; \
             var nextCalls = 0; \
             var obj = { \
               get next() { \
                 ++nextGets; \
                 var i = 0; \
                 return function () { \
                   ++nextCalls; \
                   return i < 4 ? { value: i++, done: false } : { value: undefined, done: true }; \
                 }; \
               }, \
             }; \
             var it = Iterator.from(obj); \
             var vals = []; \
             for (var k = 0; k < 5; ++k) { var r = it.next(); if (!r.done) { vals.push(r.value); } } \
             nextGets === 1 && nextCalls === 5 && vals.join(',') === '0,1,2,3'",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_from_throwing_next_getter_propagates() {
    // next getter 抛错经 from() 透传原异常，不降级为 "not iterable" TypeError。
    let mut vm = Vm::new();
    let result = eval(
        &mut vm,
        "var ok = false; \
         try { Iterator.from({ get next() { throw new RangeError('read'); } }); } \
         catch (e) { ok = e instanceof RangeError; } \
         ok",
    )
    .unwrap();
    assert!(result.as_bool());
}

#[test]
fn new_iterator_throws_type_error() {
    let mut vm = Vm::new();
    let result = eval(&mut vm, "try { new Iterator() } catch (e) { e instanceof TypeError }").unwrap();
    assert!(result.as_bool());
}

#[test]
fn iterator_from_string_full_sequence() {
    // 手动 next 逐字符取完全部 ASCII 字符后 done（游标推进路径）。
    let mut vm = Vm::new();
    let result = eval(
        &mut vm,
        "var it = Iterator.from('ab'); \
         var r = []; var x; while (!(x = it.next()).done) r.push(x.value); \
         r.join('')",
    )
    .unwrap();
    assert_eq!(to_str(&vm, result), "ab");
}

#[test]
fn iterator_from_string_astral_scalar() {
    // 字符串迭代按 Unicode 标量推进：astral 字符整体产出（标量语义未动）。
    let mut vm = Vm::new();
    let result = eval(&mut vm, "var it = Iterator.from('\\u{1F600}'); it.next().value").unwrap();
    assert_eq!(to_str(&vm, result), "\u{1F600}");
}

#[test]
fn iterator_from_string_empty_done() {
    let mut vm = Vm::new();
    let result = eval(&mut vm, "Iterator.from('').next().done").unwrap();
    assert!(result.as_bool());
}

#[test]
fn for_of_string_chars() {
    // for-of 字符串循环产出逐字符（走字节游标 + 单字符缓存）。
    let mut vm = Vm::new();
    let result = eval(&mut vm, "var out = []; for (const c of 'abc') out.push(c); out.join('')").unwrap();
    assert_eq!(to_str(&vm, result), "abc");
}

#[test]
fn iterator_proto_chain_and_self_iteration() {
    let mut vm = Vm::new();
    let cases = [
        // 各家族迭代器自迭代恒等（%IteratorPrototype% 的 @@iterator 返回 this）。
        ("var it = [1,2].values(); it[Symbol.iterator]() === it", true),
        ("var it = new Map([['a',1]]).values(); it[Symbol.iterator]() === it", true),
        ("var it = new Set([1]).values(); it[Symbol.iterator]() === it", true),
        ("var it = new Uint8Array([1]).values(); it[Symbol.iterator]() === it", true),
        ("var it = 'abc'[Symbol.iterator](); it[Symbol.iterator]() === it", true),
        ("var it = 'ab'.matchAll(/a/g); it[Symbol.iterator]() === it", true),
        // Array/TA 共享 %ArrayIteratorPrototype%；Map/Set 各自原型内部共享。
        ("Object.getPrototypeOf([].values()) === Object.getPrototypeOf([].entries())", true),
        (
            "Object.getPrototypeOf(new Uint8Array(0).values()) === Object.getPrototypeOf([].values())",
            true,
        ),
        (
            "Object.getPrototypeOf(new Map().values()) === Object.getPrototypeOf(new Map().keys())",
            true,
        ),
        (
            "Object.getPrototypeOf(new Set().values()) === Object.getPrototypeOf(new Set().entries())",
            true,
        ),
        // %IteratorPrototype% 自身可迭代：其 @@iterator 返回 this。
        (
            "var P = Object.getPrototypeOf(Object.getPrototypeOf([].values())); P[Symbol.iterator]() === P",
            true,
        ),
        // 原型链：%ArrayIteratorPrototype% → %IteratorPrototype% → Object.prototype。
        (
            "Object.getPrototypeOf(Object.getPrototypeOf([].values())) === \
             Object.getPrototypeOf(Object.getPrototypeOf(Object.getPrototypeOf([].values())))",
            false,
        ),
        (
            "Object.getPrototypeOf(Object.getPrototypeOf([].values()))[Symbol.iterator] === \
             Object.getPrototypeOf(new Map().values())[Symbol.iterator]",
            true,
        ),
    ];
    for (src, expected) in cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn array_string_symbol_iterator_bound() {
    let mut vm = Vm::new();
    // G4 别名：Array/String 的 @@iterator 属性存在且可迭代。
    let bool_cases = [
        ("[][Symbol.iterator] === [].values", true),
        ("var out = []; for (const c of 'a\\u{1F600}b') out.push(c); out.length === 3", true),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
    let str_cases = [
        ("typeof 'abc'[Symbol.iterator]", "function"),
        ("[...'ab'].join('')", "ab"),
        ("Array.from('ab').join('')", "ab"),
        ("[...[1,2,3]].join(',')", "1,2,3"),
        ("Array.from([1,2]).join(',')", "1,2"),
    ];
    for (src, expected) in str_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(to_str(&vm, result), expected, "for {}", src);
    }
    // String 迭代器语义：null/undefined 抛 TypeError，对象走 ToString。
    let err = eval(&mut vm, "try { String.prototype[Symbol.iterator].call(null) } catch (e) { e.name }").unwrap();
    assert_eq!(to_str(&vm, err), "TypeError");
    let result = eval(&mut vm, "[...String.prototype[Symbol.iterator].call({toString: () => 'xy'})].join('')").unwrap();
    assert_eq!(to_str(&vm, result), "xy");
}

#[test]
fn iterator_proto_object_proto_parent() {
    // 链：values() → %ArrayIteratorPrototype% → %IteratorPrototype% → Object.prototype。
    let mut vm = Vm::new();
    let result = eval(
        &mut vm,
        "Object.getPrototypeOf(Object.getPrototypeOf(Object.getPrototypeOf([].values()))) === Object.prototype",
    )
    .unwrap();
    assert!(result.as_bool());
}

#[test]
fn iterator_function_prototype_property() {
    // Iterator.prototype 属性绑定：=== %IteratorPrototype%（[].values() 原型链中继），
    // 且 %IteratorPrototype% 自身可迭代。
    let mut vm = Vm::new();
    let cases = [
        ("Iterator.prototype !== undefined", true),
        ("Object.getPrototypeOf(Object.getPrototypeOf([].values())) === Iterator.prototype", true),
        (
            "Object.getPrototypeOf(Object.getPrototypeOf(new Map().values())) === Iterator.prototype",
            true,
        ),
        ("Iterator.prototype[Symbol.iterator]() === Iterator.prototype", true),
    ];
    for (src, expected) in cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn string_iterator_proto_layer() {
    // String 迭代器挂 %StringIteratorPrototype% 中继层：与 Array 迭代器原型不同，
    // 且经链到 %IteratorPrototype%（Iterator.prototype）。
    let mut vm = Vm::new();
    let cases = [
        (
            "Object.getPrototypeOf(Object.getPrototypeOf('a'[Symbol.iterator]())) === Iterator.prototype",
            true,
        ),
        (
            "Object.getPrototypeOf('a'[Symbol.iterator]()) !== Object.getPrototypeOf([].values())",
            true,
        ),
    ];
    for (src, expected) in cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
    let out = eval(&mut vm, "[...'abc'].join('')").unwrap();
    assert_eq!(to_str(&vm, out), "abc");
}

#[test]
fn iterator_next_on_prototypes() {
    // next 挂集合迭代器原型（%ArrayIteratorPrototype%.next 等），wrapper 无 own next。
    let mut vm = Vm::new();
    let cases = [
        ("typeof Object.getPrototypeOf([].values()).next === 'function'", true),
        ("Object.getPrototypeOf([].values()).hasOwnProperty('next')", true),
        ("[].values().hasOwnProperty('next') === false", true),
        ("typeof Object.getPrototypeOf(new Map().values()).next === 'function'", true),
        ("new Map().values().hasOwnProperty('next') === false", true),
        ("typeof Object.getPrototypeOf(new Set().values()).next === 'function'", true),
        ("new Set().values().hasOwnProperty('next') === false", true),
        ("typeof Object.getPrototypeOf(new Uint8Array([1]).values()).next === 'function'", true),
        ("new Uint8Array([1]).values().hasOwnProperty('next') === false", true),
        ("typeof Object.getPrototypeOf('ab'.matchAll(/a/g)).next === 'function'", true),
        ("'ab'.matchAll(/a/g).hasOwnProperty('next') === false", true),
    ];
    for (src, expected) in cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_proto_next_consumption_unchanged() {
    // 行为回归：next 移上原型后各家族消费路径不变（迭代协议经原型链解析）。
    let mut vm = Vm::new();
    let str_cases = [
        ("[...[1,2,3]].join(',')", "1,2,3"),
        ("var it = [1,2].values(); it.next().value + ',' + it.next().value", "1,2"),
        ("var it = ['x','y'].entries(); it.next().value.join(':')", "0:x"),
        ("[...new Map([['a',1]])][0].join(':')", "a:1"),
        ("var mk = new Map([['k',9]]); mk.keys().next().value", "k"),
        ("var se = new Set([7]); se.entries().next().value.join(':')", "7:7"),
        ("new Uint8Array([9]).entries().next().value.join(',')", "0,9"),
        ("[...'ab'].join('')", "ab"),
        ("'a\\u{1F600}b'[Symbol.iterator]().next().value", "a"),
        ("var mm = 'ab'.matchAll(/b/g); mm.next().value[0]", "b"),
    ];
    for (src, expected) in str_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(to_str(&vm, result), expected, "for {}", src);
    }
    // 数值结果（含 int 0）用恒等比较断言，避免格式化路径差异。
    let num_cases = [
        ("[10,20].keys().next().value === 0", true),
        ("[1,2].values().next().value === 1", true),
        ("new Map([['a',1]]).values().next().value === 1", true),
        ("new Set([5,6]).keys().next().value === 5", true),
        ("new Uint8Array([5]).values().next().value === 5", true),
        ("new Uint8Array([7]).entries().next().value[1] === 7", true),
    ];
    for (src, expected) in num_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
    // TA 迭代耗尽后恒 done（数组路径 target 置 undefined 防复活）。
    let done = eval(&mut vm, "var it = new Uint8Array([1]).values(); it.next(); it.next().done").unwrap();
    assert!(done.as_bool());
}

#[test]
fn iterator_function_name_length() {
    let mut vm = Vm::new();
    let bool_cases = [
        ("Iterator.name === 'Iterator'", true),
        ("Iterator.length === 0", true),
        ("Object.getOwnPropertyDescriptor(Iterator, 'name').writable === false", true),
        ("Object.getOwnPropertyDescriptor(Iterator, 'name').enumerable === false", true),
        ("Object.getOwnPropertyDescriptor(Iterator, 'name').configurable === true", true),
        ("Object.getOwnPropertyDescriptor(Iterator, 'length').writable === false", true),
        ("Object.getOwnPropertyDescriptor(Iterator, 'length').enumerable === false", true),
        ("Object.getOwnPropertyDescriptor(Iterator, 'length').configurable === true", true),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_prototype_constructor_accessor() {
    let mut vm = Vm::new();
    let bool_cases = [
        // getter 动态读 global 上的 Iterator 构造器。
        ("Iterator.prototype.constructor === Iterator", true),
        (
            "typeof Object.getOwnPropertyDescriptor(Iterator.prototype, 'constructor').get === 'function'",
            true,
        ),
        (
            "typeof Object.getOwnPropertyDescriptor(Iterator.prototype, 'constructor').set === 'function'",
            true,
        ),
        (
            "Object.getOwnPropertyDescriptor(Iterator.prototype, 'constructor').enumerable === false",
            true,
        ),
        (
            "Object.getOwnPropertyDescriptor(Iterator.prototype, 'constructor').configurable === true",
            true,
        ),
        // getter 无参调用（this=undefined）仍返回 Iterator。
        (
            "Object.getOwnPropertyDescriptor(Iterator.prototype, 'constructor').get.call() === Iterator",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_prototype_constructor_setter_semantics() {
    let mut vm = Vm::new();
    // home 对象赋值与原始值 this 抛 TypeError（SetterThatIgnoresPrototypeProperties）。
    let throws = [
        (
            "try { Iterator.prototype.constructor = 'x'; false } catch (e) { e instanceof TypeError }",
            true,
        ),
        (
            "try { var d = Object.getOwnPropertyDescriptor(Iterator.prototype, 'constructor'); \
             d.set.call(undefined, 'x'); false } catch (e) { e instanceof TypeError }",
            true,
        ),
        (
            "try { var d = Object.getOwnPropertyDescriptor(Iterator.prototype, 'constructor'); \
             d.set.call(null, 'x'); false } catch (e) { e instanceof TypeError }",
            true,
        ),
        (
            "try { var d = Object.getOwnPropertyDescriptor(Iterator.prototype, 'constructor'); \
             d.set.call(true, 'x'); false } catch (e) { e instanceof TypeError }",
            true,
        ),
    ];
    for (src, expected) in throws {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
    // 非 home 对象：无 own 属性建 own，有 own 属性走 Set 覆盖。
    let ok_cases = [
        (
            "var o = {}; var d = Object.getOwnPropertyDescriptor(Iterator.prototype, 'constructor'); \
             d.set.call(o, 42); o.constructor === 42 && o.hasOwnProperty('constructor')",
            true,
        ),
        (
            "var o = { constructor: 1 }; var d = Object.getOwnPropertyDescriptor(Iterator.prototype, 'constructor'); \
             d.set.call(o, 2); o.constructor === 2",
            true,
        ),
        // home 不受污染。
        ("Iterator.prototype.constructor === Iterator", true),
    ];
    for (src, expected) in ok_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_prototype_to_string_tag_accessor() {
    let mut vm = Vm::new();
    let bool_cases = [
        ("Iterator.prototype[Symbol.toStringTag] === 'Iterator'", true),
        (
            "typeof Object.getOwnPropertyDescriptor(Iterator.prototype, Symbol.toStringTag).get === 'function'",
            true,
        ),
        (
            "typeof Object.getOwnPropertyDescriptor(Iterator.prototype, Symbol.toStringTag).set === 'function'",
            true,
        ),
        (
            "Object.getOwnPropertyDescriptor(Iterator.prototype, Symbol.toStringTag).enumerable === false",
            true,
        ),
        (
            "Object.getOwnPropertyDescriptor(Iterator.prototype, Symbol.toStringTag).configurable === true",
            true,
        ),
        (
            "Object.getOwnPropertyDescriptor(Iterator.prototype, Symbol.toStringTag).get.call() === 'Iterator'",
            true,
        ),
        // home 赋值抛 TypeError。
        (
            "try { Iterator.prototype[Symbol.toStringTag] = 'x'; false } catch (e) { e instanceof TypeError }",
            true,
        ),
        // 普通对象 setter 建 own Symbol.toStringTag。
        (
            "var o = {}; var d = Object.getOwnPropertyDescriptor(Iterator.prototype, Symbol.toStringTag); \
             d.set.call(o, 'tag'); o[Symbol.toStringTag] === 'tag'",
            true,
        ),
        // 原型继承场景：非 home 子对象赋值落到自身 own 属性（不污染祖先）。
        (
            "var p = Object.create(Iterator.prototype); p[Symbol.toStringTag] = 'sub'; \
             p[Symbol.toStringTag] === 'sub' && Iterator.prototype[Symbol.toStringTag] === 'Iterator'",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn symbol_dispose_and_async_dispose_registered() {
    let mut vm = Vm::new();
    // well-known symbol 以空对象表示，typeof 为 object；两符号互不相同。
    let bool_cases = [
        ("typeof Symbol.dispose === 'object'", true),
        ("typeof Symbol.asyncDispose === 'object'", true),
        ("Symbol.dispose !== Symbol.asyncDispose", true),
        ("Symbol.dispose !== Symbol.iterator", true),
        // 键可作属性名使用（well-known 键映射一致）。
        ("({ [Symbol.dispose]: 1 })[Symbol.dispose] === 1", true),
        // getOwnPropertySymbols 能反解出同一符号对象。
        ("Object.getOwnPropertySymbols({ [Symbol.dispose]: 1 })[0] === Symbol.dispose", true),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
    // 描述性名称经 String 构造器反射（well_known_symbol_name 表）。
    let desc = eval(&mut vm, "String(Symbol.dispose)").unwrap();
    assert_eq!(to_str(&vm, desc), "Symbol(Symbol.dispose)");
}

#[test]
fn iterator_prototype_symbol_dispose() {
    let mut vm = Vm::new();
    // @@dispose 调用 this 的 return 方法并返回 undefined。
    let bool_cases = [
        ("typeof Iterator.prototype[Symbol.dispose] === 'function'", true),
        ("Iterator.prototype[Symbol.dispose].length === 0", true),
        ("Iterator.prototype[Symbol.dispose].name === '[Symbol.dispose]'", true),
        (
            "var called = false; var it = { return: function() { called = true; return { done: true }; } }; \
             var r = Iterator.prototype[Symbol.dispose].call(it); r === undefined && called === true",
            true,
        ),
        // 无 return 方法：GetMethod 返回 undefined，跳过调用。
        ("Iterator.prototype[Symbol.dispose].call({ next: function() {} }) === undefined", true),
        // return 返回任意值不影响 @@dispose 的 undefined 返回值。
        (
            "var it = { return: function() { return 42; } }; \
             Iterator.prototype[Symbol.dispose].call(it) === undefined",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
    // return 抛错经 @@dispose 透传（原值，不二次包装）。
    let thrown = eval(
        &mut vm,
        "try { var it = { return: function() { throw new RangeError('boom'); } }; \
         Iterator.prototype[Symbol.dispose].call(it); false } catch (e) { e instanceof RangeError }",
    )
    .unwrap();
    assert!(thrown.as_bool());
}

#[test]
fn iterator_helper_prototype_links_to_iterator_proto() {
    let vm = Vm::new();
    // %IteratorHelperPrototype% 已建且链到 %IteratorPrototype%（链：
    // helper → %IteratorPrototype% → Object.prototype）。
    let helper_ptr = vm.session().builtin_world().iterator_helper_proto.as_ptr() as *mut JsObject;
    let helper_proto_val = unsafe { &*helper_ptr }.proto();
    let iter_ptr = vm.session().builtin_world().iterator_proto.as_ptr() as *mut JsObject;
    assert!(helper_proto_val.is_object());
    assert!(std::ptr::eq(helper_proto_val.as_js_object_ptr(), iter_ptr));
}

#[test]
fn iterator_constructor_plain_call_throws() {
    let mut vm = Vm::new();
    // 普通调用 `Iterator()` 抛 TypeError（emit 以 undefined 作 this）。
    let bool_cases = [
        ("try { Iterator(); false } catch (e) { e instanceof TypeError }", true),
        // call/apply 显式传对象 this 顶层调用同样抛（newTarget 槽为 undefined）。
        ("try { Iterator.call({}); false } catch (e) { e instanceof TypeError }", true),
        ("try { Iterator.apply({}, []); false } catch (e) { e instanceof TypeError }", true),
        // 以 %IteratorPrototype% 为原型的对象顶层调用也抛（home 形态误判保护）。
        (
            "try { Iterator.call(Object.create(Iterator.prototype)); false } \
             catch (e) { e instanceof TypeError }",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_constructor_subclassable() {
    let mut vm = Vm::new();
    // `class X extends Iterator {}` 的 super() 经放行路径返回 undefined，
    // 实例原型按 newTarget 设为 X.prototype。
    let bool_cases = [
        (
            "class TestIterator extends Iterator {} \
             var it = new TestIterator(); \
             it instanceof TestIterator && it instanceof Iterator",
            true,
        ),
        (
            "class TestIterator extends Iterator {} \
             Object.getPrototypeOf(new TestIterator()) === TestIterator.prototype",
            true,
        ),
        (
            "class TestIterator extends Iterator {} \
             Object.getPrototypeOf(TestIterator.prototype) === Iterator.prototype",
            true,
        ),
        // 显式 constructor 内 super() 与隐式等价。
        (
            "class TestIterator extends Iterator { constructor() { super(); } } \
             new TestIterator() instanceof Iterator",
            true,
        ),
        // 多层继承：newTarget 跨层保持为最外层类。
        (
            "class A extends Iterator {} class B extends A {} \
             var b = new B(); \
             b instanceof B && b instanceof A && b instanceof Iterator",
            true,
        ),
        // 构造器 name 不受影响。
        ("class TestIterator extends Iterator {} TestIterator.name === 'TestIterator'", true),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_constructor_subclass_still_rejects_new_after_reset() {
    let mut vm = Vm::new();
    // dirty reset 后构造器经 bind_iterator_global 重绑，本体与 subclass 路径不变。
    unsafe { &mut *(vm.session().builtin_world().iterator_proto.as_ptr() as *mut JsObject) }.bump_generation();
    vm.full_reset();
    let bool_cases = [
        ("try { new Iterator(); false } catch (e) { e instanceof TypeError }", true),
        (
            "class TestIterator extends Iterator {} \
             new TestIterator() instanceof Iterator",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_prototype_rebound_after_full_reset() {
    let mut vm = Vm::new();
    // 用户改写 %IteratorPrototype%：object 家族世代递增（global 未动）。
    let old_iter_proto = vm.session().builtin_world().iterator_proto.as_ptr();
    unsafe { &mut *(old_iter_proto as *mut JsObject) }.bump_generation();

    vm.full_reset();

    // %IteratorPrototype% 重建后访问器 / @@dispose 重绑正确，构造器 identity 保留。
    let cases = [
        ("Iterator.prototype.constructor === Iterator", true),
        ("Iterator.prototype[Symbol.toStringTag] === 'Iterator'", true),
        ("typeof Iterator.prototype[Symbol.dispose] === 'function'", true),
        ("Iterator.name === 'Iterator'", true),
        ("Iterator.length === 0", true),
        ("typeof Symbol.dispose === 'object'", true),
        ("typeof Symbol.asyncDispose === 'object'", true),
    ];
    for (src, expected) in cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
    // helper 原型随 object 家族重建并链到新 %IteratorPrototype%。
    let helper_ptr = vm.session().builtin_world().iterator_helper_proto.as_ptr() as *mut JsObject;
    let helper_proto_val = unsafe { &*helper_ptr }.proto();
    let new_iter_ptr = vm.session().builtin_world().iterator_proto.as_ptr() as *mut JsObject;
    assert!(std::ptr::eq(helper_proto_val.as_js_object_ptr(), new_iter_ptr));
    // 迭代器家族整体功能完好。
    let r = eval(
        &mut vm,
        "Iterator.prototype[Symbol.dispose].call({return: function(){return {done:true}}})",
    )
    .unwrap();
    assert!(r.is_undefined());
}

// ── 终端 6 方法（forEach/every/some/find/reduce/toArray）──

#[test]
fn iterator_terminal_for_each_basic() {
    // forEach 耗尽全部元素，回调收 (value, counter)，返回 undefined。
    let mut vm = Vm::new();
    let result = eval(
        &mut vm,
        "var out = []; \
         var r = Iterator.from([10, 20, 30]).forEach(function (v, i) { out.push(v + i); }); \
         out.join(',') + '|' + (r === undefined)",
    )
    .unwrap();
    assert_eq!(to_str(&vm, result), "10,21,32|true");
    let bool_cases = [
        // 普通数组迭代器（非 from 包装）同样可消费。
        ("var out = 0; [1, 2, 3].values().forEach(function (v) { out += v; }); out === 6", true),
        // 空迭代立即返回 undefined。
        ("Iterator.from([]).forEach(function () {}) === undefined", true),
        // 回调 this：规范 Call(procedure, undefined) 对 sloppy 回调仍替换为全局对象。
        (
            "var captured; Iterator.from([1]).forEach(function () { captured = this; }); \
             captured === globalThis",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_terminal_every_some_find_basic() {
    // every/some/find 正常路径：全真/短路/命中值与未命中。
    let mut vm = Vm::new();
    let bool_cases = [
        ("Iterator.from([1, 2, 3]).every(function (v) { return v > 0; }) === true", true),
        ("Iterator.from([1, 2, 3]).every(function (v) { return v > 1; }) === false", true),
        ("Iterator.from([1, 2, 3]).some(function (v) { return v > 2; }) === true", true),
        ("Iterator.from([1, 2, 3]).some(function (v) { return v > 9; }) === false", true),
        ("Iterator.from([1, 2, 3]).find(function (v) { return v > 1; }) === 2", true),
        ("Iterator.from([1, 2, 3]).find(function (v) { return v > 9; }) === undefined", true),
        // 空迭代：every/some 恒为相反端点值，find 为 undefined。
        ("Iterator.from([]).every(function () { return false; }) === true", true),
        ("Iterator.from([]).some(function () { return true; }) === false", true),
        ("Iterator.from([]).find(function () { return true; }) === undefined", true),
        // 谓词回调收 (value, counter)。
        (
            "var pairs = []; \
             Iterator.from(['a', 'b']).every(function (v, i) { pairs.push(v + i); return true; }); \
             pairs.join(',') === 'a0,b1'",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_terminal_short_circuit_closes() {
    // 短路路径关底层：only 消费到命中点，return 方法被调用。
    let mut vm = Vm::new();
    let bool_cases = [
        // some 命中后不再消费剩余元素，且底层 return 被调用。
        (
            "var reads = 0; var closed = false; \
             class CI extends Iterator { \
               next() { reads++; return reads === 1 ? { done: false, value: 1 } : { done: true, value: undefined }; } \
               return() { closed = true; return {}; } \
             } \
             var r = new CI().some(function () { return true; }); \
             r === true && closed === true && reads === 1",
            true,
        ),
        // every 首个 falsy 即短路关底层。
        (
            "var reads = 0; var closed = false; \
             class CI extends Iterator { \
               next() { reads++; return reads === 1 ? { done: false, value: 1 } : { done: true, value: undefined }; } \
               return() { closed = true; return {}; } \
             } \
             var r = new CI().every(function () { return false; }); \
             r === false && closed === true && reads === 1",
            true,
        ),
        // find 命中返回对应 value 且关底层。
        (
            "var closed = false; \
             class CI extends Iterator { \
               next() { return { done: false, value: 7 }; } \
               return() { closed = true; return {}; } \
             } \
             var r = new CI().find(function () { return true; }); \
             r === 7 && closed === true",
            true,
        ),
        // 自然耗尽（done=true）不调 return。
        (
            "var closed = false; \
             class CI extends Iterator { \
               next() { return { done: true, value: undefined }; } \
               return() { closed = true; return {}; } \
             } \
             new CI().every(function () { return true; }) === true && closed === false",
            true,
        ),
        // 短路 close 时 return getter 抛错 → 该错误胜出（正常完成形态）。
        (
            "class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               get return() { throw new RangeError('close'); } \
             } \
             try { new CI().some(function () { return true; }); false } \
             catch (e) { e instanceof RangeError }",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_terminal_reduce_basic() {
    // reduce：有/无初始值、单元素、空迭代 + 初始值、counter 语义。
    let mut vm = Vm::new();
    let bool_cases = [
        ("Iterator.from([1, 2, 3]).reduce(function (a, b) { return a + b; }) === 6", true),
        ("Iterator.from([1, 2, 3]).reduce(function (a, b) { return a + b; }, 10) === 16", true),
        ("Iterator.from([1]).reduce(function (a, b) { return a + b; }) === 1", true),
        ("Iterator.from([]).reduce(function (a, b) { return a + b; }, 99) === 99", true),
        // 无初始值：首元素作 accumulator，counter 从 1 起。
        (
            "var pairs = []; \
             Iterator.from(['a', 'b', 'c']).reduce(function (acc, v, i) { pairs.push(i); return acc; }); \
             pairs.join(',') === '1,2'",
            true,
        ),
        // 有初始值：counter 从 0 起。
        (
            "var pairs = []; \
             Iterator.from(['a', 'b']).reduce(function (acc, v, i) { pairs.push(i); return acc; }, 'x'); \
             pairs.join(',') === '0,1'",
            true,
        ),
        // accumulator 可为任意类型（含对象引用延续）。
        (
            "var acc = []; \
             Iterator.from([1, 2]).reduce(function (a, v) { a.push(v); return a; }, acc) === acc \
             && acc.join(',') === '1,2'",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_terminal_reduce_empty_no_initial_throws() {
    // 空迭代无初始值 → TypeError，且不关底层（规范字面：首步 done 直接抛）。
    let mut vm = Vm::new();
    let result = eval(
        &mut vm,
        "var closed = false; \
         class CI extends Iterator { \
           next() { return { done: true, value: undefined }; } \
           return() { closed = true; return {}; } \
         } \
         var ok = false; \
         try { new CI().reduce(function (a, b) { return a + b; }); } \
         catch (e) { ok = e instanceof TypeError; } \
         ok && closed === false",
    )
    .unwrap();
    assert!(result.as_bool());
}

#[test]
fn iterator_terminal_to_array() {
    // toArray 消费全部元素返回普通数组。
    let mut vm = Vm::new();
    let bool_cases = [
        (
            "var a = Iterator.from([1, 2, 3]).toArray(); \
             a instanceof Array && a.length === 3 && a[0] === 1 && a[2] === 3",
            true,
        ),
        (
            "var a = Iterator.from((function* () { yield 'x'; yield 'y'; })()).toArray(); \
             a instanceof Array && a.length === 2 && a[0] === 'x' && a[1] === 'y'",
            true,
        ),
        (
            "Iterator.from([]).toArray() instanceof Array && Iterator.from([]).toArray().length === 0",
            true,
        ),
        // 数组迭代器（Array.prototype.values）同样可收集。
        ("var a = [1, 2].values().toArray(); a instanceof Array && a.length === 2", true),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_terminal_callback_error_passthrough() {
    // 回调抛错：原值透传（任意类型不二次包装），且关底层。
    let mut vm = Vm::new();
    let bool_cases = [
        // 非 Error 原值 42 透传。
        (
            "try { Iterator.from([1]).forEach(function () { throw 42; }); 'no' } \
             catch (e) { e === 42 }",
            true,
        ),
        // Error 对象身份保留（不重包）。
        (
            "var sentinel = new RangeError('boom'); \
             try { Iterator.from([1]).every(function () { throw sentinel; }); 'no' } \
             catch (e) { e === sentinel }",
            true,
        ),
        // 回调抛错后底层 return 被调用，原错误仍胜出。
        (
            "var closed = false; \
             class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { closed = true; throw new RangeError('close'); } \
             } \
             var ok = false; \
             try { new CI().find(function () { throw 42; }); } \
             catch (e) { ok = e === 42; } \
             ok && closed === true",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_terminal_callback_validation_closes() {
    // 回调不可调用：抛 TypeError 且关底层，且不读 next（2024 规范更新）。
    let mut vm = Vm::new();
    let bool_cases = [
        // 无参调用（回调为 undefined）也关底层。
        (
            "var closed = false; \
             class CI extends Iterator { \
               next() { return { done: true, value: undefined }; } \
               return() { closed = true; return {}; } \
             } \
             var ok = false; \
             try { new CI().forEach(); } catch (e) { ok = e instanceof TypeError; } \
             ok && closed === true",
            true,
        ),
        // 非可调用对象同样关底层；next getter 不被读取。
        (
            "var closed = false; var read = false; \
             var it = Object.create(Iterator.prototype); \
             Object.defineProperty(it, 'next', { get: function () { read = true; return function () {}; } }); \
             it.return = function () { closed = true; return {}; }; \
             var ok = false; \
             try { it.forEach({}); } catch (e) { ok = e instanceof TypeError; } \
             ok && closed === true && read === false",
            true,
        ),
        // 回调校验失败关底层对 every/some/find/reduce 一致生效。
        (
            "var closed = false; \
             class CI extends Iterator { \
               next() { return { done: true, value: undefined }; } \
               return() { closed = true; return {}; } \
             } \
             var all = false; \
             try { new CI().some(null); } catch (e) { all = e instanceof TypeError; } \
             all && closed === true",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_terminal_reentrancy_guard() {
    // 终端方法消费期间底层生成器被重入（body 执行中再取 next）：生成器重入守卫
    // 抛 TypeError，经终端方法干净透传（不吞错、不损坏生成器状态）。
    let mut vm = Vm::new();
    let result = eval(
        &mut vm,
        "var caught = null; \
         var gen = (function* () { \
           yield 1; \
           try { Iterator.from(gen).forEach(function (v) { gen.next(); }); } \
           catch (e) { caught = e; } \
         })(); \
         gen.next(); gen.next(); \
         caught !== null && caught instanceof TypeError",
    )
    .unwrap();
    assert!(result.as_bool());
}

#[test]
fn iterator_terminal_method_shape() {
    // 6 方法 length/name 与绑定位置（挂 %IteratorPrototype% 原型）。
    let mut vm = Vm::new();
    let bool_cases = [
        (
            "Iterator.prototype.forEach.length === 1 && Iterator.prototype.every.length === 1 \
             && Iterator.prototype.some.length === 1 && Iterator.prototype.find.length === 1 \
             && Iterator.prototype.reduce.length === 1 && Iterator.prototype.toArray.length === 0",
            true,
        ),
        (
            "Iterator.prototype.forEach.name === 'forEach' && Iterator.prototype.every.name === 'every' \
             && Iterator.prototype.some.name === 'some' && Iterator.prototype.find.name === 'find' \
             && Iterator.prototype.reduce.name === 'reduce' && Iterator.prototype.toArray.name === 'toArray'",
            true,
        ),
        // 方法经原型链对普通对象可用（this 为任意对象即可）。
        (
            "var it = { next: function () { return { done: true, value: undefined }; } }; \
             Iterator.prototype.toArray.call(it) instanceof Array",
            true,
        ),
        // this 非对象 → TypeError。
        (
            "try { Iterator.prototype.forEach.call(1, function () {}); false } \
             catch (e) { e instanceof TypeError }",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_terminal_rebound_after_full_reset() {
    // dirty reset 后 6 终端方法随 %IteratorPrototype% 重建重绑，功能完好。
    let mut vm = Vm::new();
    unsafe { &mut *(vm.session().builtin_world().iterator_proto.as_ptr() as *mut JsObject) }.bump_generation();
    vm.full_reset();
    let bool_cases = [
        ("Iterator.from([1, 2, 3]).forEach(function () {}) === undefined", true),
        (
            "var out = []; \
             Iterator.from(['a', 'b']).forEach(function (v) { out.push(v); }); out.join('') === 'ab'",
            true,
        ),
        ("Iterator.from([1, 2]).reduce(function (a, b) { return a + b; }, 0) === 3", true),
        ("Iterator.from([1, 2]).toArray().length === 2", true),
        ("Iterator.from([1]).some(function () { return true; }) === true", true),
        ("Iterator.from([1]).every(function () { return true; }) === true", true),
        ("Iterator.from([1]).find(function () { return true; }) === 1", true),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

// ── 返回迭代器 5 方法（map/filter/take/drop/flatMap）+ helper 状态机 ──

#[test]
fn iterator_helper_map_filter_basic() {
    // map/filter 正常路径：产出、counter 实参、回调 this 为 undefined。
    let mut vm = Vm::new();
    let str_cases = [
        ("[...Iterator.from([1, 2, 3]).map(function (v) { return v * 2; })].join(',')", "2,4,6"),
        // 数组迭代器（非 from 包装）同样可消费。
        ("[...[1, 2, 3].values().map(function (v) { return v + 10; })].join(',')", "11,12,13"),
        // filter 只产出 truthy 元素。
        (
            "[...Iterator.from([1, 2, 3, 4]).filter(function (v) { return v % 2 === 0; })].join(',')",
            "2,4",
        ),
        // 谓词返回值被 ToBoolean 化。
        ("[...Iterator.from([0, 1, 2]).filter(function (v) { return v; })].join(',')", "1,2"),
        // map 回调收 (value, counter)。
        (
            "var pairs = []; \
             var it = Iterator.from(['a', 'b']).map(function (v, i) { pairs.push(v + i); return v; }); \
             var x; \
             while (!(x = it.next()).done) {} \
             pairs.join(',')",
            "a0,b1",
        ),
        // filter 计数含被过滤元素（0 被过滤但占用计数 0，命中元素用计数 1）。
        (
            "var pairs = []; \
             var it = Iterator.from([0, 1, 2]).filter(function (v, i) { pairs.push(i); return v > 0; }); \
             var x; \
             while (!(x = it.next()).done) {} \
             pairs.join(',')",
            "0,1,2",
        ),
    ];
    for (src, expected) in str_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(to_str(&vm, result), expected, "for {}", src);
    }
    let bool_cases = [
        // 回调 this：规范 Call(procedure, undefined) 对 sloppy 回调仍替换为全局对象。
        (
            "var captured; Iterator.from([1]).map(function () { captured = this; return 1; }).next(); \
             captured === globalThis",
            true,
        ),
        // 空迭代立即 done。
        ("Iterator.from([]).map(function (v) { return v; }).next().done", true),
        // 方法 length 均为 1。
        ("Iterator.prototype.map.length === 1 && Iterator.prototype.filter.length === 1", true),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_helper_take_drop_basic() {
    // take/drop 正常路径：计数边界、limit 校验、自然耗尽。
    let mut vm = Vm::new();
    let str_cases = [
        ("[...Iterator.from([1, 2, 3]).take(2)].join(',')", "1,2"),
        ("[...Iterator.from([1, 2, 3]).take(5)].join(',')", "1,2,3"),
        ("[...Iterator.from([1, 2, 3]).take(0)].join(',')", ""),
        ("[...Iterator.from([1, 2, 3]).take(Infinity)].join(',')", "1,2,3"),
        ("[...Iterator.from([1, 2, 3]).drop(2)].join(',')", "3"),
        ("[...Iterator.from([1, 2, 3]).drop(0)].join(',')", "1,2,3"),
        ("[...Iterator.from([1, 2, 3]).drop(10)].join(',')", ""),
        ("[...Iterator.from([1, 2, 3]).drop(Infinity)].join(',')", ""),
        // 链式组合。
        ("[...Iterator.from([1, 2, 3, 4, 5]).drop(1).take(3)].join(',')", "2,3,4"),
    ];
    for (src, expected) in str_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(to_str(&vm, result), expected, "for {}", src);
    }
    let bool_cases = [
        // -0.5 → trunc(-0) 合法；null → 0 合法。
        ("[...Iterator.from([1]).take(-0.5)].join(',') === ''", true),
        ("[...Iterator.from([1, 2]).take(null)].join(',') === ''", true),
        ("[...Iterator.from([1, 2]).drop(null)].join(',') === '1,2'", true),
        // limit 经 valueOf/toString 强制转换。
        (
            "var n = { valueOf: function () { return 1; } }; \
             [...Iterator.from([1, 2]).take(n)].join(',') === '1'",
            true,
        ),
        (
            "var n = { toString: function () { return '1'; } }; \
             [...Iterator.from([1, 2]).drop(n)].join(',') === '2'",
            true,
        ),
        // 方法 length 均为 1。
        ("Iterator.prototype.take.length === 1 && Iterator.prototype.drop.length === 1", true),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_helper_take_drop_limit_validation() {
    // NaN/负值/缺失 limit → RangeError 且关底层；ToNumber 抛错原值透传且关底层；
    // next getter 在 limit 校验前不被读取。
    let mut vm = Vm::new();
    let bool_cases = [
        // take()/take(undefined)/NaN/-1 → RangeError。
        (
            "var closed = 0; \
             var c = { __proto__: Iterator.prototype, get next() { throw new RangeError('read'); }, \
                       return() { closed++; return {}; } }; \
             var ok = false; \
             try { c.take(); } catch (e) { ok = e instanceof RangeError; } \
             ok && closed === 1",
            true,
        ),
        (
            "var closed = 0; \
             var c = { __proto__: Iterator.prototype, get next() { throw new RangeError('read'); }, \
                       return() { closed++; return {}; } }; \
             var ok = false; \
             try { c.take(NaN); } catch (e) { ok = e instanceof RangeError; } \
             ok && closed === 1",
            true,
        ),
        (
            "var closed = 0; \
             var c = { __proto__: Iterator.prototype, get next() { throw new RangeError('read'); }, \
                       return() { closed++; return {}; } }; \
             var ok = false; \
             try { c.drop(-1); } catch (e) { ok = e instanceof RangeError; } \
             ok && closed === 1",
            true,
        ),
        // limit valueOf 抛错：原异常透传且关底层。
        (
            "var closed = 0; \
             var c = { __proto__: Iterator.prototype, get next() { throw new RangeError('read'); }, \
                       return() { closed++; return {}; } }; \
             var boom = new RangeError('boom'); \
             var ok = false; \
             try { c.take({ valueOf: function () { throw boom; } }); } catch (e) { ok = e === boom; } \
             ok && closed === 1",
            true,
        ),
        // 校验失败不读 next（getter 抛错也不触发）。
        (
            "var closed = 0; var read = false; \
             var c = { __proto__: Iterator.prototype, \
                       get next() { read = true; return function () {}; }, \
                       return() { closed++; return {}; } }; \
             var ok = false; \
             try { c.take(-1); } catch (e) { ok = e instanceof RangeError; } \
             ok && closed === 1 && read === false",
            true,
        ),
        // this 非对象：直接 TypeError，不读 limit/不关。
        (
            "var ok = false; \
             try { Iterator.prototype.take.call(1, 0); } catch (e) { ok = e instanceof TypeError; } \
             ok",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_helper_take_exhaustion_closes() {
    // take 达标即关底层（return 被调用）；自然耗尽不关；关后再调 next 全短路。
    let mut vm = Vm::new();
    let bool_cases = [
        // take(0)：首个 next 即关底层（return 抛错传播）。
        (
            "var closed = 0; \
             class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { closed++; throw new RangeError('boom'); } \
             } \
             var it = new CI().take(0); \
             var threw = false; \
             try { it.next(); } catch (e) { threw = e instanceof RangeError; } \
             it.next().done && threw && closed === 1",
            true,
        ),
        // take(1)：取 1 个后第二次 next 关底层。
        (
            "var closed = 0; \
             class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { closed++; return {}; } \
             } \
             var it = new CI().take(1); \
             it.next().value === 1 && it.next().done && closed === 1",
            true,
        ),
        // take(5) 但底层 3 个：自然耗尽不关底层。
        (
            "var closed = 0; \
             var i = 0; \
             class CI extends Iterator { \
               next() { i++; return i <= 3 ? { done: false, value: i } : { done: true, value: undefined }; } \
               return() { closed++; return {}; } \
             } \
             var out = 0; \
             var it = new CI().take(5); \
             var x; \
             while (!(x = it.next()).done) out += x.value; \
             out === 6 && closed === 0",
            true,
        ),
        // return 方法转发：显式 return() 关底层且只关一次。
        (
            "var closed = 0; \
             class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { closed++; return {}; } \
             } \
             var it = new CI().take(100); \
             it.return(); it.return(); \
             closed === 1",
            true,
        ),
        // return getter 抛错：return() 时该错误胜出。
        (
            "class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               get return() { throw new RangeError('boom'); } \
             } \
             var it = new CI().take(1); \
             it.next(); \
             var threw = false; \
             try { it.return(); } catch (e) { threw = e instanceof RangeError; } \
             threw",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_helper_drop_exhaustion_no_close() {
    // drop 耗尽/跳过永不主动关底层；return() 转发仍生效。
    let mut vm = Vm::new();
    let bool_cases = [
        // drop(10) 消耗 3 个元素后自然耗尽，return 不被调用。
        (
            "var closed = 0; \
             var i = 0; \
             class CI extends Iterator { \
               next() { i++; return i <= 3 ? { done: false, value: i } : { done: true, value: undefined }; } \
               return() { closed++; return {}; } \
             } \
             var it = new CI().drop(10); \
             var x; \
             while (!(x = it.next()).done) {} \
             closed === 0",
            true,
        ),
        // 显式 return() 关底层且只关一次。
        (
            "var closed = 0; \
             class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { closed++; return {}; } \
             } \
             var it = new CI().drop(1); \
             it.return(); it.return(); \
             closed === 1",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_helper_flat_map_semantics() {
    // flatMap 正常路径：数组/生成器/纯 next 对象展开、回退路径、原始值拒绝。
    let mut vm = Vm::new();
    let str_cases = [
        // mapper 返回数组：经 @@iterator 展开。
        ("[...Iterator.from([1, 2]).flatMap(function (v) { return [v, v * 10]; })].join(',')", "1,10,2,20"),
        // mapper 返回生成器。
        (
            "[...Iterator.from([1, 2]).flatMap(function (v) { return (function* () { yield v; yield v + 1; })(); })].join(',')",
            "1,2,2,3",
        ),
        // mapper 返回纯 next 对象（无 @@iterator，回退鸭子 next）。
        (
            "function* h() { yield 0; yield 1; yield 2; } \
             var it = Iterator.from([1]).flatMap(function () { \
               var n = h(); \
               return { [Symbol.iterator]: null, next: function () { return n.next(); } }; \
             }); \
             [...it].join(',')",
            "0,1,2",
        ),
        // 空数组内层：跳过并继续外层。
        ("[...Iterator.from([1, 2]).flatMap(function () { return []; })].join(',')", ""),
        // counter 只按外层元素递增。
        (
            "var pairs = []; \
             var it = Iterator.from(['a', 'b']).flatMap(function (v, i) { pairs.push(v + i); return [v]; }); \
             var x; \
             while (!(x = it.next()).done) {} \
             pairs.join(',')",
            "a0,b1",
        ),
        // 字符串包装对象可展开（对象走 @@iterator）。
        ("[...Iterator.from([1]).flatMap(function () { return new String('ab'); })].join(',')", "a,b"),
    ];
    for (src, expected) in str_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(to_str(&vm, result), expected, "for {}", src);
    }
    let bool_cases = [
        // 已关闭的生成器作内层：首次 next 即 done，直接回到外层。
        (
            "function* g() { yield 0; yield 1; yield 2; } \
             var closed = g(); \
             closed.return(); \
             closed.return = function () { throw new RangeError('boom'); }; \
             var it = g().flatMap(function (v) { return closed; }); \
             it.next().done",
            true,
        ),
        // mapper 返回原始值（含字符串）→ TypeError。
        (
            "var it = Iterator.from([1]).flatMap(function () { return 5; }); \
             var ok = false; \
             try { it.next(); } catch (e) { ok = e instanceof TypeError; } \
             ok",
            true,
        ),
        (
            "var it = Iterator.from([1]).flatMap(function () { return 'str'; }); \
             var ok = false; \
             try { it.next(); } catch (e) { ok = e instanceof TypeError; } \
             ok",
            true,
        ),
        // @@iterator 非 null/undefined 且不可调用 → TypeError。
        (
            "var it = Iterator.from([1]).flatMap(function () { return { [Symbol.iterator]: 0, next: function () {} }; }); \
             var ok = false; \
             try { it.next(); } catch (e) { ok = e instanceof TypeError; } \
             ok",
            true,
        ),
        // @@iterator 结果非对象 → TypeError。
        (
            "var it = Iterator.from([1]).flatMap(function () { return { [Symbol.iterator]: function () { return 5; } }; }); \
             var ok = false; \
             try { it.next(); } catch (e) { ok = e instanceof TypeError; } \
             ok",
            true,
        ),
        // 方法 length 为 1。
        ("Iterator.prototype.flatMap.length === 1", true),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_helper_wrapper_proto_and_shape() {
    // wrapper 挂 %IteratorHelperPrototype%：instanceof Iterator、原型链、
    // 三方法 + @@toStringTag、无 own next。
    let mut vm = Vm::new();
    let bool_cases = [
        ("Iterator.from([1]).map(function (x) { return x; }) instanceof Iterator", true),
        (
            "var it = Iterator.from([1]).filter(function () { return true; }); \
             Object.getPrototypeOf(it)[Symbol.toStringTag] === 'Iterator Helper'",
            true,
        ),
        (
            "var it = Iterator.from([1]).take(1); \
             Object.getPrototypeOf(it) !== Iterator.prototype \
             && Object.getPrototypeOf(Object.getPrototypeOf(it)) === Iterator.prototype",
            true,
        ),
        (
            "var p = Object.getPrototypeOf(Iterator.from([1]).map(function (x) { return x; })); \
             typeof p.next === 'function' && typeof p.return === 'function' && typeof p.throw === 'function'",
            true,
        ),
        // next/return length 0，throw length 1。
        (
            "var p = Object.getPrototypeOf(Iterator.from([1]).map(function (x) { return x; })); \
             p.next.length === 0 && p.return.length === 0 && p.throw.length === 1",
            true,
        ),
        // helper 原型经原型链可迭代（%IteratorPrototype% 的 @@iterator）。
        (
            "var p = Object.getPrototypeOf(Iterator.from([1]).map(function (x) { return x; })); \
             p[Symbol.iterator]() === p",
            true,
        ),
        // 5 方法 name/描述符。
        (
            "Iterator.prototype.map.name === 'map' && Iterator.prototype.filter.name === 'filter' \
             && Iterator.prototype.take.name === 'take' && Iterator.prototype.drop.name === 'drop' \
             && Iterator.prototype.flatMap.name === 'flatMap'",
            true,
        ),
        (
            "var d = Object.getOwnPropertyDescriptor(Iterator.prototype, 'map'); \
             d.writable === true && d.enumerable === false && d.configurable === true",
            true,
        ),
        // this 非对象 → TypeError。
        (
            "try { Iterator.prototype.map.call(1, function () {}); false } \
             catch (e) { e instanceof TypeError }",
            true,
        ),
        // 非 helper 对象调用原型 next → TypeError。
        (
            "var p = Object.getPrototypeOf(Iterator.from([1]).map(function (x) { return x; })); \
             var ok = false; \
             try { p.next.call({}); } catch (e) { ok = e instanceof TypeError; } \
             ok",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_helper_return_throw_state_machine() {
    // return/throw 三方法状态机：转发、完成态短路、错误胜出。
    let mut vm = Vm::new();
    let bool_cases = [
        // return 转发底层且只关一次。
        (
            "var closed = 0; \
             class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { closed++; return {}; } \
             } \
             var it = new CI().map(function (x) { return x; }); \
             it.next(); \
             it.return(); it.return(); \
             closed === 1 && it.next().done",
            true,
        ),
        // 自然耗尽后 return 不转发。
        (
            "var closed = 0; \
             class CI extends Iterator { \
               next() { return { done: true, value: undefined }; } \
               return() { closed++; return {}; } \
             } \
             var it = new CI().map(function (x) { return x; }); \
             it.next(); \
             it.return(); \
             closed === 0",
            true,
        ),
        // 底层 return 抛错：return() 传播该错误，此后 next 全 done。
        (
            "class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { throw new RangeError('boom'); } \
             } \
             var it = new CI().map(function (x) { return x; }); \
             var threw = false; \
             try { it.return(); } catch (e) { threw = e instanceof RangeError; } \
             threw && it.next().done && it.return().done",
            true,
        ),
        // throw 注入：置完成 + 关底层 + 原值传播。
        (
            "var closed = 0; \
             class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { closed++; return {}; } \
             } \
             var it = new CI().map(function (x) { return x; }); \
             var ok = false; \
             try { it.throw(42); } catch (e) { ok = e === 42; } \
             ok && closed === 1 && it.next().done",
            true,
        ),
        // 完成态 throw：直接抛值（不关底层）。
        (
            "var closed = 0; \
             class CI extends Iterator { \
               next() { return { done: true, value: undefined }; } \
               return() { closed++; return {}; } \
             } \
             var it = new CI().map(function (x) { return x; }); \
             it.next(); \
             var ok = false; \
             try { it.throw(7); } catch (e) { ok = e === 7; } \
             ok && closed === 0",
            true,
        ),
        // throw 时底层 return 也抛错：原值胜出。
        (
            "class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { throw new RangeError('close'); } \
             } \
             var it = new CI().map(function (x) { return x; }); \
             var ok = false; \
             try { it.throw(42); } catch (e) { ok = e === 42; } \
             ok",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_helper_flat_map_return_closes_inner_then_outer() {
    // flatMap 内层活跃时 return：先关内层再关外层；内层 return 错误优先胜出。
    let mut vm = Vm::new();
    let bool_cases = [
        (
            "var innerClosed = 0; var outerClosed = 0; \
             var it = Iterator.from([1]).flatMap(function (v) { \
               return { next: function () { return { done: false, value: 1 }; }, \
                        return: function () { innerClosed++; return {}; } }; \
             }); \
             it.next(); \
             it.return(); \
             innerClosed === 1",
            true,
        ),
        // 外层 return 错误传播（内层正常关闭后）。
        (
            "var outerClosed = 0; \
             class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { outerClosed++; throw new RangeError('boom'); } \
             } \
             var it = new CI().flatMap(function (v) { \
               return { next: function () { return { done: false, value: 1 }; }, \
                        return: function () { return {}; } }; \
             }); \
             it.next(); \
             var threw = false; \
             try { it.return(); } catch (e) { threw = e instanceof RangeError; } \
             threw && outerClosed === 1",
            true,
        ),
        // 内层 return 错误优先于外层。
        (
            "var innerClosed = 0; \
             class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { return {}; } \
             } \
             var it = new CI().flatMap(function (v) { \
               return { next: function () { return { done: false, value: 1 }; }, \
                        return: function () { innerClosed++; throw new RangeError('inner'); } }; \
             }); \
             it.next(); \
             var ok = false; \
             try { it.return(); } catch (e) { ok = e instanceof RangeError; } \
             ok && innerClosed === 1",
            true,
        ),
        // 内层未起步（未 next）时 return 只关外层。
        (
            "var outerClosed = 0; \
             class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { outerClosed++; return {}; } \
             } \
             var it = new CI().flatMap(function (v) { return [v]; }); \
             it.return(); \
             outerClosed === 1",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_helper_reentrancy_guard() {
    // 5 方法重入守卫：推进期间再调 next → TypeError，且底层不被二次推进。
    let mut vm = Vm::new();
    let bool_cases = [
        // map：mapper 内重入。
        (
            "var enterCount = 0; \
             var gen = (function* () { yield 1; })(); \
             var it = gen.map(function (v) { enterCount++; it.next(); return v; }); \
             var ok = false; \
             try { it.next(); } catch (e) { ok = e instanceof TypeError; } \
             ok && enterCount === 1",
            true,
        ),
        // filter：谓词内重入。
        (
            "var enterCount = 0; \
             var gen = (function* () { yield 1; })(); \
             var it = gen.filter(function (v) { enterCount++; it.next(); return true; }); \
             var ok = false; \
             try { it.next(); } catch (e) { ok = e instanceof TypeError; } \
             ok && enterCount === 1",
            true,
        ),
        // take：底层 next 内重入。
        (
            "var enterCount = 0; \
             class CI extends Iterator { \
               next() { enterCount++; it.next(); return { done: false, value: 1 }; } \
             } \
             var it = new CI().take(100); \
             var ok = false; \
             try { it.next(); } catch (e) { ok = e instanceof TypeError; } \
             ok && enterCount === 1",
            true,
        ),
        // drop：底层 next 内重入。
        (
            "var enterCount = 0; \
             class CI extends Iterator { \
               next() { enterCount++; it.next(); return { done: false, value: 1 }; } \
             } \
             var it = new CI().drop(0); \
             var ok = false; \
             try { it.next(); } catch (e) { ok = e instanceof TypeError; } \
             ok && enterCount === 1",
            true,
        ),
        // flatMap：mapper 内重入。
        (
            "var enterCount = 0; \
             var gen = (function* () { yield 1; })(); \
             var it = gen.flatMap(function (v) { enterCount++; it.next(); return [v]; }); \
             var ok = false; \
             try { it.next(); } catch (e) { ok = e instanceof TypeError; } \
             ok && enterCount === 1",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_helper_callback_error_passthrough() {
    // 回调抛错：原值透传（任意类型不二次包装），且关底层。
    let mut vm = Vm::new();
    let bool_cases = [
        // 非 Error 原值 42 透传。
        (
            "var closed = 0; \
             class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { closed++; return {}; } \
             } \
             var it = new CI().map(function () { throw 42; }); \
             var ok = false; \
             try { it.next(); } catch (e) { ok = e === 42; } \
             ok && closed === 1",
            true,
        ),
        // filter 谓词抛错同样处理。
        (
            "var sentinel = new RangeError('boom'); \
             class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { return {}; } \
             } \
             var it = new CI().filter(function () { throw sentinel; }); \
             var ok = false; \
             try { it.next(); } catch (e) { ok = e === sentinel; } \
             ok",
            true,
        ),
        // 回调抛错且底层 return 也抛错：原错误胜出。
        (
            "class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { throw new RangeError('close'); } \
             } \
             var it = new CI().map(function () { throw 42; }); \
             var ok = false; \
             try { it.next(); } catch (e) { ok = e === 42; } \
             ok",
            true,
        ),
        // 回调抛错后 helper 完成：再调 next 全 done。
        (
            "class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { return {}; } \
             } \
             var it = new CI().map(function () { throw 42; }); \
             var ok = false; \
             try { it.next(); } catch (e) { ok = e === 42; } \
             ok && it.next().done",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_helper_validation_failure_closes() {
    // 回调不可调用：抛 TypeError 且关底层，且不读 next（2024 规范更新）。
    let mut vm = Vm::new();
    let bool_cases = [
        (
            "var closed = 0; \
             var c = { __proto__: Iterator.prototype, get next() { throw new RangeError('read'); }, \
                       return() { closed++; return {}; } }; \
             var ok = false; \
             try { c.map(); } catch (e) { ok = e instanceof TypeError; } \
             ok && closed === 1",
            true,
        ),
        (
            "var closed = 0; \
             var c = { __proto__: Iterator.prototype, get next() { throw new RangeError('read'); }, \
                       return() { closed++; return {}; } }; \
             var ok = false; \
             try { c.flatMap({}); } catch (e) { ok = e instanceof TypeError; } \
             ok && closed === 1",
            true,
        ),
        (
            "var closed = 0; var read = false; \
             var c = { __proto__: Iterator.prototype, \
                       get next() { read = true; return function () {}; }, \
                       return() { closed++; return {}; } }; \
             var ok = false; \
             try { c.filter(null); } catch (e) { ok = e instanceof TypeError; } \
             ok && closed === 1 && read === false",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_helper_get_next_only_once_and_parallel() {
    // next getter 只在建 wrapper 时读一次；底层可被并行推进（共享同一底层）。
    let mut vm = Vm::new();
    let bool_cases = [
        // 5 方法各自只读一次 next。
        (
            "var gets = 0; \
             class C extends Iterator { \
               get next() { gets++; return function () { return { done: true, value: undefined }; }; } \
             } \
             new C().map(function (x) { return x; }); \
             new C().filter(function () { return true; }); \
             new C().take(1); \
             new C().drop(1); \
             new C().flatMap(function () { return []; }); \
             gets === 5",
            true,
        ),
        // 底层直接推进后 helper 从当前位置继续。
        (
            "var it = (function* () { for (var i = 0; i < 5; ++i) yield i; })(); \
             var mapped = it.map(function (x) { return x; }); \
             it.next(); \
             mapped.next().value === 1 && mapped.next().value === 2",
            true,
        ),
        // 底层提前关闭后 helper 立即 done。
        (
            "var it = (function* () { for (var i = 0; i < 5; ++i) yield i; })(); \
             var mapped = it.map(function (x) { return x; }); \
             it.return(); \
             mapped.next().done",
            true,
        ),
        // 底层 next 返回非对象：helper next 抛 TypeError（不关底层）。
        (
            "class CI extends Iterator { \
               next() { return null; } \
               return() { throw new RangeError('boom'); } \
             } \
             var it = new CI().map(function (x) { return x; }); \
             var ok = false; \
             try { it.next(); } catch (e) { ok = e instanceof TypeError; } \
             ok",
            true,
        ),
        // flatMap 内层 next 抛错：关外层不关内层。
        (
            "var outerClosed = 0; \
             class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { outerClosed++; return {}; } \
             } \
             var innerClosed = 0; \
             var it = new CI().flatMap(function (v) { \
               return { next: function () { throw new RangeError('inner'); }, \
                        return: function () { innerClosed++; return {}; } }; \
             }); \
             var ok = false; \
             try { it.next(); } catch (e) { ok = e instanceof RangeError; } \
             ok && outerClosed === 1 && innerClosed === 0",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_helper_generator_proto_chain() {
    // %GeneratorPrototype% 链到 %IteratorPrototype%：生成器可调用全部 helper。
    let mut vm = Vm::new();
    let bool_cases = [
        (
            "Object.getPrototypeOf(Object.getPrototypeOf(function* () {}.prototype)) === Iterator.prototype",
            true,
        ),
        (
            "var gen = (function* () { yield 1; yield 2; })(); \
             Object.getPrototypeOf(Object.getPrototypeOf(Object.getPrototypeOf(gen))) === Iterator.prototype",
            true,
        ),
        // 生成器实例直接可用 5 helper。
        (
            "var g = (function* () { yield 1; yield 2; yield 3; })(); \
             [...g.map(function (x) { return x * 2; })].join(',') === '2,4,6'",
            true,
        ),
        (
            "var g = (function* () { yield 1; yield 2; yield 3; })(); \
             [...g.filter(function (x) { return x > 1; })].join(',') === '2,3'",
            true,
        ),
        (
            "var g = (function* () { yield 1; yield 2; yield 3; })(); \
             [...g.take(2)].join(',') === '1,2'",
            true,
        ),
        (
            "var g = (function* () { yield 1; yield 2; yield 3; })(); \
             [...g.drop(1)].join(',') === '2,3'",
            true,
        ),
        (
            "var g = (function* () { yield 1; })(); \
             [...g.flatMap(function (x) { return [x, x]; })].join(',') === '1,1'",
            true,
        ),
        // 生成器结果对象是 Iterator。
        ("(function* () {})().map(function (x) { return x; }) instanceof Iterator", true),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_helper_plain_call_and_edge_cases() {
    // 非 Iterator 子类但实现迭代协议的 this（.call 路径）、已耗尽底层、
    // next getter 抛错、非可调用底层 next。
    let mut vm = Vm::new();
    let bool_cases = [
        // .call 在纯 next 对象上可用（this-plain-iterator）。
        (
            "var it = { next: function () { var i = 0; return function () { i++; \
               return i <= 2 ? { done: false, value: i } : { done: true }; }; }() }; \
             var m = Iterator.prototype.map.call(it, function (x) { return x * 2; }); \
             var out = []; \
             var x; \
             while (!(x = m.next()).done) out.push(x.value); \
             out.join(',') === '2,4'",
            true,
        ),
        // 已耗尽底层：map 结果首个 next 即 done。
        (
            "var it = (function* () {})(); \
             it.next(); \
             it.map(function (x) { return x; }).next().done",
            true,
        ),
        // next getter 在方法调用时抛错：原错误透传（回调合法时读 next）。
        (
            "class TI extends Iterator { get next() { throw new RangeError('boom'); } } \
             var ok = false; \
             try { new TI().map(function (x) { return x; }); } catch (e) { ok = e instanceof RangeError; } \
             ok",
            true,
        ),
        // 底层 next 非可调用：建 wrapper 成功，首个 helper next 抛 TypeError。
        (
            "var it = Iterator.prototype.map.call({ next: 0 }, function (x) { return x; }); \
             var ok = false; \
             try { it.next(); } catch (e) { ok = e instanceof TypeError; } \
             ok",
            true,
        ),
        // 底层在 map 之前被关闭：helper next 立即 done。
        (
            "var it = (function* () { yield 1; })(); \
             it.return(); \
             var m = it.map(function (x) { return x; }); \
             m.next().done",
            true,
        ),
        // 链式 map×3 的 return 逐层关闭到底层。
        (
            "var closed = 0; \
             class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { closed++; throw new RangeError('boom'); } \
             } \
             var it = new CI().map(function (x) { return x; }).map(function (x) { return x; }); \
             var threw = false; \
             try { it.return(); } catch (e) { threw = e instanceof RangeError; } \
             threw && closed === 1",
            true,
        ),
        // flatMap 内层返回 [Symbol.iterator]: 0（不可调用）→ TypeError 且关外层。
        (
            "var outerClosed = 0; \
             class CI extends Iterator { \
               next() { return { done: false, value: 1 }; } \
               return() { outerClosed++; return {}; } \
             } \
             var it = new CI().flatMap(function () { return { [Symbol.iterator]: 0, next: function () {} }; }); \
             var ok = false; \
             try { it.next(); } catch (e) { ok = e instanceof TypeError; } \
             ok && outerClosed === 1",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}

#[test]
fn iterator_helper_rebound_after_full_reset() {
    // dirty reset 后 5 返回迭代器方法 + helper 原型三方法重绑正确。
    let mut vm = Vm::new();
    unsafe { &mut *(vm.session().builtin_world().iterator_proto.as_ptr() as *mut JsObject) }.bump_generation();
    vm.full_reset();
    let bool_cases = [
        (
            "var out = []; \
             var it = Iterator.from([1, 2, 3]).map(function (v) { return v * 2; }); \
             var x; \
             while (!(x = it.next()).done) out.push(x.value); \
             out.join(',') === '2,4,6'",
            true,
        ),
        (
            "var it = Iterator.from([1, 2, 3]).filter(function (v) { return v % 2 === 1; }); \
             [...it].join(',') === '1,3'",
            true,
        ),
        (
            "var it = Iterator.from([1, 2, 3]).take(2); \
             [...it].join(',') === '1,2'",
            true,
        ),
        (
            "var it = Iterator.from([1, 2, 3]).drop(1); \
             [...it].join(',') === '2,3'",
            true,
        ),
        (
            "var it = Iterator.from([1, 2]).flatMap(function (v) { return [v, v]; }); \
             [...it].join(',') === '1,1,2,2'",
            true,
        ),
        (
            "var it = Iterator.from([1]).map(function (x) { return x; }); \
             Object.getPrototypeOf(it)[Symbol.toStringTag] === 'Iterator Helper'",
            true,
        ),
        // 生成器原型链在 reset 后仍指向新 %IteratorPrototype%。
        (
            "Object.getPrototypeOf(Object.getPrototypeOf(function* () {}.prototype)) === Iterator.prototype",
            true,
        ),
        // helper 三方法可用。
        (
            "var it = Iterator.from([1, 2]).map(function (x) { return x; }); \
             it.return().done === true",
            true,
        ),
    ];
    for (src, expected) in bool_cases {
        let result = eval(&mut vm, src).unwrap();
        assert_eq!(result.as_bool(), expected, "for {}", src);
    }
}