selectedCheckboxTest.cs

    @Test
    public void checkboxes() {
        driver.get("https://the-internet.herokuapp.com/checkboxes");
        WebElement firstCheckbox = driver.findElement(By.xpath("//input[1]"));
        if (!firstCheckbox.isSelected()) {
            firstCheckbox.click();
        }
        Assert.assertTrue(firstCheckbox.isSelected());
    }