michael@0: // The LHS of a for-loop is not bound to a particular scope until after the .next() method returns.
michael@0: 
michael@0: var obj = {};
michael@0: 
michael@0: // Test 1
michael@0: function g() {
michael@0:     obj.x = 0;
michael@0:     yield 1;
michael@0: }
michael@0: var x = 2, n = 0;
michael@0: with (obj) {
michael@0:     for (x of g())  // g().next() inserts a binding for x on obj
michael@0:         n++;
michael@0: }
michael@0: assertEq(x, 2);
michael@0: assertEq(obj.x, 1);
michael@0: assertEq(n, 1);
michael@0: 
michael@0: // Test 2
michael@0: function h() {
michael@0:     delete obj.x;
michael@0:     yield 3;
michael@0: }
michael@0: n = 0;
michael@0: with (obj) {
michael@0:     for (x of h())  // h().next() deletes the binding for x on obj
michael@0:         n++;
michael@0: }
michael@0: assertEq(x, 3);
michael@0: assertEq("x" in obj, false);
michael@0: assertEq(n, 1);