fix: nested for...of

app/astride/sandbox.js

@@ -38,6 +38,7 @@ export default class Sandbox {
         if (
           'BlockStatement' === node.type
           || 'ForStatement' === node.type
+          || 'ForOfStatement' === node.type
         ) {
           switch (verb) {
             case 'enter': {
@@ -325,14 +326,17 @@ export default class Sandbox {
           }
           scope.allocate('@@iterator', right.value[Symbol.iterator]());
         }
-        if (this.$$execution.stack[depth + 1] === node) {
-          this.$$execution.stack.pop();
-        }
         result = this.$$execution.deferred.get(node.body) || {
           value: undefined,
           yield: YIELD_NONE,
         };
-        const {done, value} = scope.get('@@iterator').next();
+        if (shouldVisitChild(node)) {
+          this.$$execution.deferred.set(node.left, scope.get('@@iterator').next());
+        }
+        if (this.$$execution.stack[depth + 1] === node) {
+          this.$$execution.stack.pop();
+        }
+        const {done, value} = this.$$execution.deferred.get(node.left);
         if (done) {
           this.$$execution.deferred.delete(node.body);
           break;

app/astride/sandbox.test.js

@@ -536,4 +536,20 @@ test('implements for...of', async () => {
     )).run()
   )
     .to.deep.include({value: [2, 12, 30]});
+  context.iterable = [{x: [[1, 2], [3, 4], [5, 6]]}];
+  expect(
+    (new Sandbox(
+      await parse(`
+        const mapped = [];
+        for (const {x} of iterable) {
+          for (const [y, z] of x) {
+            mapped.push(y * z);
+          }
+        }
+        mapped
+      `),
+      context,
+    )).run()
+  )
+    .to.deep.include({value: [2, 12, 30]});
 });