JSTests/stress/set-add-check-failure.js

function shouldBe(actual, expected) {
    if (actual !== expected)
        throw new Error('bad value: ' + actual);
}

function shouldThrow(func, errorMessage) {
    var errorThrown = false;
    var error = null;
    try {
        func();
    } catch (e) {
        errorThrown = true;
        error = e;
    }
    if (!errorThrown)
        throw new Error('not thrown');
    if (String(error) !== errorMessage)
        throw new Error(`bad error: ${String(error)}`);
}

var func = Set.prototype.add;
function target(set)
{
    return func.call(set, 42);
}
noInline(target);

for (var i = 0; i < 1e6; ++i) {
    var set = new Set();
    shouldBe(target(set), set);
    shouldBe(set.has(42), true);
}
shouldThrow(() => {
    target(new Map());
}, `TypeError: Set operation called on non-Set object`);