JSTests/stress/string-repeat-edge-cases.js

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

{
    let object = {
        toString()
        {
            return "C";
        }
    };
    shouldBe(String.prototype.repeat.call(object, 2.5), "CC");
    shouldBe(String.prototype.repeat.call(object, -0), "");
    shouldBe(String.prototype.repeat.call(object, 1), "C");
    shouldBe(String.prototype.repeat.call(object, {
        valueOf()
        {
            return 2.5;
        }
    }), "CC");
    shouldThrow(() => {
        String.prototype.repeat.call(object, {
            valueOf()
            {
                throw new Error("OK");
            }
        });
    }, `Error: OK`);
}

{
    shouldBe(String.prototype.repeat.call("", 0), "");
    shouldBe(String.prototype.repeat.call("", 0xFFFFFFFFF), "");
    shouldThrow(() => {
        String.prototype.repeat.call("", Infinity);
    }, `RangeError: String.prototype.repeat argument must be greater than or equal to 0 and not be Infinity`);

    shouldThrow(() => {
        String.prototype.repeat.call("", -2000);
    }, `RangeError: String.prototype.repeat argument must be greater than or equal to 0 and not be Infinity`);
}