How to set Chrome preferences using Selenium Webdriver .NET binding?

Question

Here is what I'm using, user agent can be successfully set, while download preferences cannot.

Windows 7, Chrome 26, Selenium-dotnet-2.31.2, chromedriver_win_26.0.1383.0

ChromeOptions chromeOptions = new ChromeOptions();
var prefs = new Dictionary<string, object> {
    { "download.default_directory", @"C:\code" },
    { "download.prompt_for_download", false }
};
chromeOptions.AddAdditionalCapability("chrome.prefs", prefs);
chromeOptions.AddArgument("--user-agent=" + "some safari agent");
var driver = new ChromeDriver(chromeOptions);

Taken from chromedriver.log:

[1.201][FINE]:      Initializing session with capabilities {

   "browserName": "chrome",

   "chrome.prefs": {

      "download.default_directory": "C:\\code",

      "download.prompt_for_download": false

   },

   "chrome.switches": [ "--user-agent=Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/534.57.2 (KHTML, like Gecko) Version..." ],

   "chromeOptions": {

      "args": [ "--user-agent=Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/534.57.2 (KHTML, like Gecko) Version..." ],

      "binary": "",

      "extensions": [  ]

   },

   "javascriptEnabled": true,

   "platform": "WINDOWS",

   "version": ""

}

Check the temp Preferences file at *temp\Google\Chrome\User Data\Default\Preferences, no "default_directory" and "prompt_for_download" are set.

   "download": {
      "directory_upgrade": true
   },

Answer 1

The Selenium dotNet driver does not support setting the chrome.prefs out of the box. The problem is that chrome.prefs must be defined as prefs under the chromeOptions node. The ChromeOptions class does not contain this variable, so you'll need to create your own ChromeOptions class:

public class ChromeOptionsWithPrefs: ChromeOptions
{
    public Dictionary<string,object> prefs { get; set; }
}

public static void Initialize()
{
    var options = new ChromeOptionsWithPrefs();
    options.prefs = new Dictionary<string, object>
    {
        { "intl.accept_languages", "nl" }
    };
    _driver = new ChromeDriver(@"C:\path\chromedriver", options);
}