var r;
Object.defineProperty(this, "x", {value: 0, writable: false});
for (var a = 0; a < 10; ++a)
r = ++x;
assertEq(x, 0);
assertEq(r, 1);
for (var a = 0; a < 10; ++a)
r = --x;
assertEq(x, 0);
assertEq(r, -1);
for (var a = 0; a < 10; ++a)
r = x++;
assertEq(x, 0);
assertEq(r, 0);
for (var a = 0; a < 10; ++a)
r = x--;
assertEq(x, 0);
assertEq(r, 0);