HeadlessTestsExecutionTests.cs

private void PerformTestOperations(IWebDriver driver)
{
    string testPagePath = 
        "http://htmlpreview.github.io/?https://github.com/angelovstanton/AutomateThePlanet/blob/master/WebDriver-Series/TestPage.html";
    driver.Navigate().GoToUrl(testPagePath);
    driver.Manage().Timeouts().PageLoad = TimeSpan.FromSeconds(10);
    driver.Manage().Timeouts().ImplicitWait = TimeSpan.FromSeconds(10);
    var textBoxes = driver.FindElements(By.Name("fname"));
    foreach (var textBox in textBoxes)
    {
        textBox.SendKeys(Guid.NewGuid().ToString());
    }

    var selects = driver.FindElements(By.TagName("select"));
    foreach (var select in selects)
    {
        var selectElement = new SelectElement(select);
        selectElement.SelectByText("Mercedes");
    }

    var submits = driver.FindElements(By.XPath("//input[@type='submit']"));
    foreach (var submit in submits)
    {
        submit.Click();
    }

    var colors = driver.FindElements(By.XPath("//input[@type='color']"));
    foreach (var color in colors)
    {
        SetValueAttribute(driver, color, "#000000");
    }

    var dates = driver.FindElements(By.XPath("//input[@type='date']"));
    foreach (var date in dates)
    {
        SetValueAttribute(driver, date, "2020-06-01");
    }

    var radioButtons = driver.FindElements(By.XPath("//input[@type='radio']"));
    foreach (var radio in radioButtons)
    {
        radio.Click();
    }
}

private void SetValueAttribute(IWebDriver driver, IWebElement element, string value)
{
    SetAttribute(driver, element, "value", value);
}

private void SetAttribute(IWebDriver driver, IWebElement element, string attributeName, string attributeValue)
{
    driver.ExecuteJavaScript
    (
        "arguments[0].setAttribute(arguments[1], arguments[2]);",
        element,
        attributeName,
        attributeValue);
}