BUnit render component to string deadlocks when using in a Blazor context > 1.18.4

[biohazard999]

I use BUnit to render a component to a string inside a blazor application to support rendering markdown.

Currently i'm using it somewhat like this:

var context = new TestContext();

context.Services.AddFallbackServiceProvider(ServiceProvider);

var rendered = context.Render(ChildContent);
var markup = MarkdownStringUtils.TrimLeftSpaces(rendered.Markup);

var html = Markdown.ToHtml(markup, Pipeline);
_markupString = new MarkupString(html);

All versions after 1.18.4 end in a deadlock rendering the component to html

I guess the crucket is here: 7c15692

I tried to wrap my code into a InvokeAsync etc but still get deadlocked (the render pipeline just never passes Render(ChildContent)).

I know this is not the primary use case for bunit, and i am waiting for the native net8.0 implementation to render a component to a string from microsoft.

Are there any workarounds i could use?

I could provide a small repro if needed.

[egil]

I could provide a small repro if needed.

Yes please. I'd be very curious to see what is in the RenderFragment.

You can also try the latest preview 1.22.xx. It attempts to solve the #1064 issue which may be related.

[biohazard999]

@egil here you go: https://github.com/biohazard999/bunit-repro-1144

does not change with the latest preview. Double checked downgrade to 1.18.4 works as expected.

[egil]

Thanks. I'll try to take a look in the coming days.

[biohazard999]

This allows me to write markdown in blazor components (and also do some nice stuff related to interpreting the markdown)

Thank you! :) If it's out of scope for bunit, a hint how to do this on my own is also very appreciated.

[egil]

I think it is sort of out of scope, but it should also work without problems, so I want to understand what's going on because it could also affect others in test scenarios.

That said, as part of net 8, the functionality you need will be built-in to the framework. Look for the blog post for preview 2 or 3 for details.

[biohazard999]

Given you are on net8.0 preview 3 you can define a MarkdownRenderer.razor component:

@ChildContent
@code {
    [Parameter]
    public RenderFragment ChildContent { get; set; } = default!;
}

After that it's possible to workaround like so:

ILoggerFactory loggerFactory = ServiceProvider.GetRequiredService<ILoggerFactory>();

await using var htmlRenderer = new HtmlRenderer(ServiceProvider, loggerFactory);

var markup = await htmlRenderer.Dispatcher.InvokeAsync(async () =>
{
    var parameters = ParameterView.FromDictionary(new Dictionary<string, object?>
    {
        [nameof(MarkdownRenderer.ChildContent)] = ChildContent
    });

    var output = await htmlRenderer.RenderComponentAsync<MarkdownRenderer>(parameters);
    return output.ToHtmlString();
});

markup = MarkdownStringUtils.TrimLeftSpaces(markup);

var html = Markdown.ToHtml(markup, Pipeline);
_markupString = new MarkupString(html);

This should be a hint for other's how to workaround this problem.

I will stick with 1.18.4 for my net6.0 impl and drop bunit in production for > net8.0.

Thanks @egil :)

[egil]

@biohazard999 can you try again with the 1.22.16-preview release and see if that solves the issue for you.

[biohazard999]

@egil works 👏👏

[egil]

Great. Still have a few other issues to solve before we make a none-preview release.