Hello I’m trying to write a unit test for a custom IPublishedContent extension method.

The extension method looks like this…

public static string GetAltText(this IPublishedContent iPublishedContent)
{
    string description = iPublishedContent.Value<string>("alternativeText");

    if (string.IsNullOrEmpty(description))
    {
        return iPublishedContent.Name;
    }

    return description;    
}

I've tried a number of ways but end up with the same error message…

System.TypeInitializationException : The type initializer for 'Umbraco.Extensions.FriendlyPublishedContentExtensions' threw an exception. ----> System.ArgumentNullException : Value cannot be null. (Parameter 'provider')

One attempt was to use a wrapper class but I’m not sure if I am even approached it correctly.

public interface IExtensionMethodTest
{
    string GetAltText();
}

public class ExtensionMethodTest : IExtensionMethodTest
{
    private readonly IPublishedContent _iPublishedContent;

    public ExtensionMethodTest(IPublishedContent iPublishedContent)
    {
        _iPublishedContent = iPublishedContent;
    }

    public string GetAltText()
    {
        return _iPublishedContent.GetAltText();
    } 
}

[Test]
[TestCase("GetAltText")]
public void GetAltText(string getAltText)
{
    Mock<IPublishedContent>  publishedContent = new Mock<IPublishedContent>();

    var wrapper = new ExtensionMethodTest(publishedContent.Object);

    var result = wrapper.GetAltText();

    Assert.AreEqual(getAltText, result);
}

I’m using Umbraco 11.2.0.

Any help would be greatly appreciated.

Thanks.