dotnet/src/WebDriver.Support/UI/ExpectedConditions.cs

// <copyright file="ExpectedConditions.cs" company="WebDriver Committers">
// Copyright 2007-2011 WebDriver committers
// Copyright 2007-2011 Google Inc.
// Portions copyright 2011 Software Freedom Conservancy
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// </copyright>

using System;
using System.Collections.Generic;
using System.Text;

namespace OpenQA.Selenium.Support.UI
{
    /// <summary>
    /// Supplies a set of common conditions that can be waited for using <see cref="WebDriverWait"/>.
    /// </summary>
    /// <example>
    /// <code>
    /// IWait wait = new WebDriverWait(driver, TimeSpan.FromSeconds(3))
    /// IWebElement element = wait.Until(ExpectedConditions.ElementExists(By.Id("foo")));
    /// </code>
    /// </example>
    public sealed class ExpectedConditions
    {
        /// <summary>
        /// Prevents a default instance of the <see cref="ExpectedConditions"/> class from being created.
        /// </summary>
        private ExpectedConditions()
        {
        }

        /// <summary>
        /// An expectation for checking the title of a page.
        /// </summary>
        /// <param name="title">The expected title, which must be an exact match.</param>
        /// <returns><see langword="true"/> when the title matches; otherwise, <see langword="false"/>.</returns>
        public static Func<IWebDriver, bool> TitleIs(string title)
        {
            return (driver) => { return title == driver.Title; };
        }

        /// <summary>
        /// An expectation for checking that the title of a page contains a case-sensitive substring.
        /// </summary>
        /// <param name="title">The fragment of title expected.</param>
        /// <returns><see langword="true"/> when the title matches; otherwise, <see langword="false"/>.</returns>
        public static Func<IWebDriver, bool> TitleContains(string title)
        {
            return (driver) => { return driver.Title.Contains(title); };
        }

        /// <summary>
        /// An expectation for checking that an element is present on the DOM of a
        /// page. This does not necessarily mean that the element is visible.
        /// </summary>
        /// <param name="locator">The locator used to find the element.</param>
        /// <returns>The <see cref="IWebElement"/> once it is located.</returns>
        public static Func<IWebDriver, IWebElement> ElementExists(By locator)
        {
            return (driver) => { return driver.FindElement(locator); };
        }

        /// <summary>
        /// An expectation for checking that an element is present on the DOM of a page
        /// and visible. Visibility means that the element is not only displayed but
        /// also has a height and width that is greater than 0.
        /// </summary>
        /// <param name="locator">The locator used to find the element.</param>
        /// <returns>The <see cref="IWebElement"/> once it is located and visible.</returns>
        public static Func<IWebDriver, IWebElement> ElementIsVisible(By locator)
        {
            return (driver) =>
                {
                    try
                    {
                        return ElementIfVisible(driver.FindElement(locator));
                    }
                    catch (StaleElementReferenceException)
                    {
                        return null;
                    }
                };
        }

        private static IWebElement ElementIfVisible(IWebElement element)
        {
            if (element.Displayed)
            {
                return element;
            }
            else
            {
                return null;
            }
        }
    }
}