fix: 字符串默认迭代器缺失时按不可迭代抛错

crates/oxide_vm/tests/string_iterator_removed_tests.rs

@@ -0,0 +1,298 @@
+//! String 臂默认迭代器删除/null/undefined 形钉：`String.prototype[Symbol.iterator]`
+//! 缺失时 for-of/spread/解构/`Iterator.from`/`new Set` 按不可迭代抛 TypeError，
+//! `Array.from`/`%TypedArray%.from` 落 array-like 按 UTF-16 单元产出；默认迭代器
+//! 在位的正常路径不回归。
+
+use std::sync::Arc;
+
+use oxide_compiler::compiler::Compiler;
+use oxide_types::value::JsValue;
+use oxide_vm::vm::Vm;
+
+fn run(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))?;
+    let mut vm = Vm::new();
+    vm.run(&Arc::new(module))
+}
+
+/// 断言 IIFE 求值为 `true`（把多断言收敛为布尔，规避 JsValue Display 只暴露
+/// number/bool 的限制）。
+fn assert_truthy(name: &str, source: &str) {
+    let result = run(source).unwrap_or_else(|e| panic!("{name}: {e}"));
+    assert!(result.as_bool(), "{name}: expected truthy, got {:?}", result);
+}
+
+#[test]
+fn for_of_string_throws_after_delete() {
+    // 原始串：删除默认迭代器后不再码元步进，按不可迭代抛 TypeError。
+    assert_truthy(
+        "for-of primitive delete",
+        r#"(function(){
+            delete String.prototype[Symbol.iterator];
+            try { for (var c of "ab") {} return false; }
+            catch (e) { return e instanceof TypeError; }
+        })()"#,
+    );
+    // 装箱串同形。
+    assert_truthy(
+        "for-of boxed delete",
+        r#"(function(){
+            delete String.prototype[Symbol.iterator];
+            try { for (var c of new String("ab")) {} return false; }
+            catch (e) { return e instanceof TypeError; }
+        })()"#,
+    );
+}
+
+#[test]
+fn spread_and_destructure_string_throw_after_delete() {
+    assert_truthy(
+        "spread primitive delete",
+        r#"(function(){
+            delete String.prototype[Symbol.iterator];
+            try { [..."ab"]; return false; }
+            catch (e) { return e instanceof TypeError; }
+        })()"#,
+    );
+    assert_truthy(
+        "destructure primitive delete",
+        r#"(function(){
+            delete String.prototype[Symbol.iterator];
+            try { var [a, b] = "ab"; return false; }
+            catch (e) { return e instanceof TypeError; }
+        })()"#,
+    );
+}
+
+#[test]
+fn iterator_from_string_throws_after_delete() {
+    // GetIteratorFlattenable：原始串与装箱串均按不可迭代抛 TypeError。
+    assert_truthy(
+        "Iterator.from primitive delete",
+        r#"(function(){
+            delete String.prototype[Symbol.iterator];
+            try { Iterator.from("ab"); return false; }
+            catch (e) { return e instanceof TypeError; }
+        })()"#,
+    );
+    assert_truthy(
+        "Iterator.from boxed delete",
+        r#"(function(){
+            delete String.prototype[Symbol.iterator];
+            try { Iterator.from(new String("ab")); return false; }
+            catch (e) { return e instanceof TypeError; }
+        })()"#,
+    );
+}
+
+#[test]
+fn set_constructor_string_throws_after_delete() {
+    assert_truthy(
+        "new Set primitive delete",
+        r#"(function(){
+            delete String.prototype[Symbol.iterator];
+            try { new Set("ab"); return false; }
+            catch (e) { return e instanceof TypeError; }
+        })()"#,
+    );
+    assert_truthy(
+        "new Set boxed delete",
+        r#"(function(){
+            delete String.prototype[Symbol.iterator];
+            try { new Set(new String("ab")); return false; }
+            catch (e) { return e instanceof TypeError; }
+        })()"#,
+    );
+}
+
+#[test]
+fn null_and_undefined_forms_throw() {
+    // null 与 undefined 两形与删除同判：GetMethod 解析为空 → 不可迭代。
+    assert_truthy(
+        "for-of null",
+        r#"(function(){
+            String.prototype[Symbol.iterator] = null;
+            try { for (var c of "ab") {} return false; }
+            catch (e) { return e instanceof TypeError; }
+        })()"#,
+    );
+    assert_truthy(
+        "for-of undefined",
+        r#"(function(){
+            String.prototype[Symbol.iterator] = undefined;
+            try { for (var c of "ab") {} return false; }
+            catch (e) { return e instanceof TypeError; }
+        })()"#,
+    );
+}
+
+#[test]
+fn array_from_string_falls_back_to_array_like_after_delete() {
+    // 删除默认迭代器后 Array.from 走 array-like，按 UTF-16 码元逐个产出，不抛。
+    assert_truthy(
+        "Array.from primitive delete",
+        r#"(function(){
+            delete String.prototype[Symbol.iterator];
+            var r = Array.from("ab");
+            return r.length === 2 && r[0] === "a" && r[1] === "b";
+        })()"#,
+    );
+    assert_truthy(
+        "Array.from boxed delete",
+        r#"(function(){
+            delete String.prototype[Symbol.iterator];
+            var r = Array.from(new String("ab"));
+            return r.length === 2 && r[0] === "a" && r[1] === "b";
+        })()"#,
+    );
+}
+
+#[test]
+fn array_from_string_null_and_undefined_fall_back() {
+    assert_truthy(
+        "Array.from null",
+        r#"(function(){
+            String.prototype[Symbol.iterator] = null;
+            var r = Array.from("ab");
+            return r.length === 2 && r[0] === "a" && r[1] === "b";
+        })()"#,
+    );
+    assert_truthy(
+        "Array.from undefined",
+        r#"(function(){
+            String.prototype[Symbol.iterator] = undefined;
+            var r = Array.from("ab");
+            return r.length === 2 && r[0] === "a" && r[1] === "b";
+        })()"#,
+    );
+}
+
+#[test]
+fn array_from_string_falls_back_to_code_units_after_delete() {
+    // array-like 口径是 UTF-16 码元：代理对拆成两个孤立 surrogate，不合并成码点。
+    assert_truthy(
+        "Array.from gclef delete",
+        r#"(function(){
+            delete String.prototype[Symbol.iterator];
+            var r = Array.from("\uD834\uDD1E");
+            return r.length === 2 && r[0] === "\uD834" && r[1] === "\uDD1E";
+        })()"#,
+    );
+}
+
+#[test]
+fn array_from_string_mapfn_on_array_like_path() {
+    // array-like 回退仍逐元素应用 mapFn，索引按码元位置。
+    assert_truthy(
+        "Array.from mapFn delete",
+        r#"(function(){
+            delete String.prototype[Symbol.iterator];
+            var r = Array.from("ab", function(c, i){ return c + i; });
+            return r.length === 2 && r[0] === "a0" && r[1] === "b1";
+        })()"#,
+    );
+}
+
+#[test]
+fn array_from_generic_array_like_unaffected() {
+    // 非字符串 array-like 源不受字符串分支影响。
+    assert_truthy(
+        "Array.from object",
+        r#"(function(){
+            delete String.prototype[Symbol.iterator];
+            var r = Array.from({ length: 2, 0: "a", 1: "b" });
+            return r.length === 2 && r[0] === "a" && r[1] === "b";
+        })()"#,
+    );
+}
+
+#[test]
+fn typed_array_from_string_falls_back_after_delete() {
+    // %TypedArray%.from 同前置门：删除后落 array-like，按单元取值再 ToNumber。
+    assert_truthy(
+        "Uint8Array.from delete",
+        r#"(function(){
+            delete String.prototype[Symbol.iterator];
+            var u = Uint8Array.from("ab");
+            return u.length === 2 && u[0] === 0 && u[1] === 0;
+        })()"#,
+    );
+}
+
+#[test]
+fn non_callable_iterator_method_throws_for_optional_entry() {
+    // 非空不可调用方法是 GetMethod 步 4 的 TypeError，不得落 array-like。
+    assert_truthy(
+        "42 for-of",
+        r#"(function(){
+            String.prototype[Symbol.iterator] = 42;
+            try { for (var c of "ab") {} return false; }
+            catch (e) { return e instanceof TypeError; }
+        })()"#,
+    );
+    assert_truthy(
+        "42 Array.from",
+        r#"(function(){
+            String.prototype[Symbol.iterator] = 42;
+            try { Array.from("ab"); return false; }
+            catch (e) { return e instanceof TypeError; }
+        })()"#,
+    );
+}
+
+#[test]
+fn peek_getter_sees_primitive_receiver() {
+    // Array.from 的可迭代性探测经 String.prototype 读 @@iterator，receiver 为原始值。
+    assert_truthy(
+        "Array.from getter receiver",
+        r#"(function(){
+            var orig = String.prototype[Symbol.iterator];
+            var obs;
+            Object.defineProperty(String.prototype, Symbol.iterator, {
+                get: function(){ "use strict"; obs = typeof this; return orig; }
+            });
+            var r = Array.from("ab");
+            return obs === "string" && r.length === 2 && r[0] === "a";
+        })()"#,
+    );
+}
+
+#[test]
+fn array_from_string_object_ignores_duck_next_after_delete() {
+    // 装箱串 @@iterator 缺失时按 array-like（规范只查 @@iterator）：即便对象自身有
+    // 可调用 next，也不走鸭子迭代路径、不因 get_iterator 无 duck 回退而误抛。
+    assert_truthy(
+        "Array.from boxed duck-next delete",
+        r#"(function(){
+            var s = new String("zz");
+            s.next = function(){ return { value: "DUCK", done: false }; };
+            delete String.prototype[Symbol.iterator];
+            var r = Array.from(s);
+            return r.length === 2 && r[0] === "z" && r[1] === "z";
+        })()"#,
+    );
+}
+
+#[test]
+fn default_string_iterator_regression() {
+    // 默认迭代器在位：码点快速路径不变（抽象字符单个元素），各消费者逐字符。
+    assert_truthy(
+        "default string iterator",
+        r#"(function(){
+            var chars = "";
+            for (var c of "ab") chars += c;
+            var spread = [..."ab"].join("");
+            var destructured = (function(){ var [a, b] = "ab"; return a + b; })();
+            var from = Array.from("ab").join("");
+            var fromIterator = Array.from(Iterator.from("ab")).join("");
+            var gclef = Array.from("\uD834\uDD1E");
+            var direct = String.prototype[Symbol.iterator].call("ab");
+            return chars === "ab" && spread === "ab" && destructured === "ab"
+                && from === "ab" && fromIterator === "ab"
+                && gclef.length === 1 && gclef[0] === "\uD834\uDD1E"
+                && direct.next().value === "a" && direct.next().value === "b";
+        })()"#,
+    );
+}