JSTests/stress/global-add-function-should-not-be-shadowed-by-lexical-bindings.js

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)}`);
}

shouldThrow(() => {
    $.evalScript(`const shouldThrow = 42`);
}, `SyntaxError: Can't create duplicate variable that shadows a global property: 'shouldThrow'`);