List all by content Type

Hi all !
I'm new to Episerver.

Version 11.13.0.0

I created a ContentData TestContent class which looks like this :

public class TestContent : ContentData, IContent
    {
        //IContent implementation
        public string Name { get; set; }
        public ContentReference ContentLink { get; set; }
        public ContentReference ParentLink  { get; set; }
        public Guid ContentGuid  { get; set; }
        public int ContentTypeID  { get; set; }
        public bool IsDeleted { get; set; }
        //Test Entity implementation
        public virtual string TestName { get; set; }
        public virtual int TestNumber { get; set; }
        public virtual string Text { get; set; }
    }

Then I saved a sample through Controller as following:

public ActionResult Index()
{
    var contentRepository = ServiceLocator.Current.GetInstance<IContentRepository>();
    var testContent = contentRepository.GetDefault<TestContent.TestContent> 
     (ContentReference.RootPage);
            testContent.Name = "Test2";
            testContent.TestName = "Testing name";
            testContent.TestNumber = 25;
            testContent.Text = "Testing text2";
    contentRepository.Save(testContent, Security.AccessLevel.Administer);
    return View();
}

Then I checked in database that it did saved as i wanted and it is a success.

My question: I want to be able to get a list of all the things I saved earlier of this content type which is TestContent from a controller.

Thanks for all help