Any reason bUnit behaves differently to blazor when AuthenticationStateChanged?

[oatsoda]

I hope you don't mind the slightly open-ended question, but I'm struggling with an issue in bUnit compared to the behaviour in Blazor.

It seems to be around the AuthenticationStateChanged being raised - specifically, moving from a state of Not Authenticated -> Authenticated.

In the Blazor app, when this occurs my @page component is removed from the render tree and replaced with a new instance of the same @page component (I am not 100% why, but possibly because the Blazor renderer treats changes to authentication state as requiring any existing components rendered as "dirty" or "unsafe" and therefore creates brand new instances?).

Are you aware of any reason why bUnit might not reproduce this behaviour?

Appreciate it is quite open ended, but any clues may help. I may be able to cut down some code and make a small repro if not.

[egil]

Without example code, it is hard to say for certain, but my best guess is that the @page attribute is used by the routing system in Blazor, so unless you actually render your component under test in bUnit inside the <Router> component, then the behavior is not going to be the same.

bUnit does not do anything in particular with the @page attribute, and neither does the core Blazor runtime. It's just used by the router system, which is not part of a bUnit test by default.

[oatsoda]

Thanks for the reply @egil. I am rendering the component in the <Router>. Appreciate you're probably going to say that's not expected, but I'm using bUnit for TDD and not component/unit testing, so I don't want to tie the tests to the internal component structures.

So my issue: I was thinking it was either a bUnit renderer issue or some subtle different in behaviour in of the Router when under test. I'm also wondering if it could be a sync context issue.

Thanks for confirming there's nothing special in the bUnit renderer regarding @page attributes.

[oatsoda]

If you're interested, this is roughly my approach:

private readonly TestContext _testContext;

public IServiceCollection Services => _testContext.Services;
public IServiceProvider ServiceProvider => _testContext.Services;

Services.AddProductionDependencies(config);

public IRenderedComponent<App> Build(string relativeUrl)
{
   var nav = ServiceProvider.GetRequiredService<FakeNavigationManager>();
   nav.NavigateTo($"{nav.BaseUri.TrimEnd('/')}{relativeUrl}");

   return _testContext.RenderComponent<App>();
}

[egil]

That looks like a good solution.

[oatsoda]

I've asked a question on the aspnetcore discussions Q&A so I'll see if I can get any more detail - dotnet/aspnetcore#49024