Adding cascading parameters with parameterbuilder using expression-based .Add() does not work correctly.

[benjaminsampica]

Describe the bug or question
The bUnit section here describes three different ways of populating cascading parameters. The first and second way do currently work, but the third however does not. This tripped me up for an hour while I finally narrowed it down to bUnit being the issue.

The below classes/tests are all pulled directly from the above docs.

Example:
Testing this component:

    public class CascadingParams : ComponentBase
    {
        [CascadingParameter]
        public bool IsDarkTheme { get; set; }

        [CascadingParameter(Name = "LoggedInUser")]
        public string UserName { get; set; }

        [CascadingParameter(Name = "LoggedInEmail")]
        public string Email { get; set; }
    }

With this test:

            using var ctx = new TestContext();
            var isDarkTheme = true;

            // Using factory method
            var cut1 = ctx.RenderComponent<CascadingParams>(
              CascadingValue(isDarkTheme)
            );

            // Using parameter builder
            var cut2 = ctx.RenderComponent<CascadingParams>(parameters => parameters
              .Add(isDarkTheme)
            );

            // Using parameter builder and selecting unnamed cascading parameter
            var cut3 = ctx.RenderComponent<CascadingParams>(parameters => parameters
              .Add(p => p.IsDarkTheme, isDarkTheme)
            );

            cut1.Instance.IsDarkTheme.Should().BeTrue();
            cut2.Instance.IsDarkTheme.Should().BeTrue();
            cut3.Instance.IsDarkTheme.Should().BeTrue();

Results in this output:

Result Message:	Expected cut3.Instance.IsDarkTheme to be true, but found False.

Expected behavior:
cut3 assertion should be true.

Version info:

• Library version: 1.0.0-beta-9
• .NET Core/Blazor version: 3.1, 5.0

Additional context:

[egil]

Hi @benjaminsampica

Thanks for bringing this to my attention and apologies for the inconvenience. It seems this slipped through code review and that's not good enough!

If you want to take a crack at this please let me know. PR's are welcome.

[benjaminsampica]

Thanks, I'll take a crack at this and see if I can figure it out.

[egil]

Great. Feel free to open a draft pull request to get feedback as you go.

I think it's basically these two files you need to be concerned with:

• https://github.com/egil/bUnit/blob/dev/src/bunit.core/ComponentParameterFactory.cs
• https://github.com/egil/bUnit/blob/dev/tests/bunit.core.tests/ComponentParameterFactoryTest.cs

If you are up for it, there are related issues, i.e. #169 and #178. The latter is highly related I think and might be worth looking at at the same time.

[benjaminsampica]

@egil I've looked at this for a while and just can't figure it out. It seems that everything is in order until TestRenderer.GetComponent() is iterated through, at which point the component returned does not contain the value. Diving into that further there is a RenderTreeFrame that contains the unnamed cascading value attributes, that are all correct, exactly like the named cascading value. However, the RenderTreeFrame child component that is returned does not contain the unnamed cascading key/value, whereas the named cascading value is correctly filled out.

Unfortunately, I just don't know enough about this, my apologies. Draft is here with the failing test.

[egil]

No apologies necessary. Thanks for taking the time. I will look into this as soon as possible.

[egil]

Fix available in the latest nightly available on GPR. See #209 for guide on how to test it.