bUnit: Change Uri in NavigationManager from async method in component is not always visible in test

Describe the bug

I have a OnValidSubmit which triggers the HandleValidSubmit method. This updates my data and afterwards triggers my navigationmanager to redirect. When I test it within browser redirection works fine but in my test it returns navMan.Uri => "http://localhost/"

Example: Testing this component:

@page "/Angebot-erstellen"

<div class="container">
    <div class="row">
        <div class="col-md-12">
            <div class="card shadow mb-3">
                <div class="card-header py-3">
                    <h4 class="m-0 font-weight-bold">Angebot erstellen</h4>
                                <EditForm Model="@_currProposal" OnValidSubmit="@HandleValidSubmit">
                                        <label class="h4 mt-2">Titel</label><InputText @bind-Value="_currProposal.Title" class="form-control" type="text" required="" minlength="3"/><label class="h4 mt-2">Beschreibung</label><InputTextArea @bind-Value="_currProposal.Description" class="form-control" style="margin-top: 11px;" required="" minlength="10" rows="5"/><label class="h4 mt-2">Branche</label>
                                        <InputSelect @bind-Value="_currProposal.Field" class="form-control form-control-sm custom-select custom-select-sm h5">
                                            <option value="0" selected="">Bitte Branche auswählen...</option>
                                            <option value="Architektur/Bau/Immobilien">Architektur/Bau/Immobilien</option>
                                            <option value="Automobil">Automobil</option>
                                            <option value="Banken/Finanzsektor/Versicherung">Banken/Finanzsektor/Versicherung</option>
                                            <option value="Beratung">Beratung</option>
                                            <option value="Bildung">Bildung</option>
                                            <option value="Chemie">Chemie</option>
                                            <option value="Dienstleistung">Dienstleistung</option>
                                            <option value="Druck/Verpackung">Druck/Verpackung</option>
                                            <option value="IT">IT</option>
                                            <option value="Elektro/Elektronik">Elektro/Elektronik</option>
                                            <option value="Energie">Energie</option>
                                            <option value="Forschung/Entwicklung">Forschung/Entwicklung</option>
                                            <option value="Gesundheit/Soziales/Pflege">Gesundheit/Soziales/Pflege</option>
                                            <option value="Kunst/Kultur">Kunst/Kultur</option>
                                            <option value="Landwirtschaft/Nahrungsmittel">Landwirtschaft/Nahrungsmittel</option>
                                            <option value="Logistik/Transport/Verkehr">Logistik/Transport/Verkehr</option>
                                            <option value="Luft- und Raumfahrt">Luft- und Raumfahrt</option>
                                            <option value="Marketing/Werbung/PR">Marketing/Werbung/PR</option>
                                            <option value="Maschinen- und Anlagenbau">Maschinen- und Anlagenbau</option>
                                            <option value="Medizin/Pharma">Medizin/Pharma</option>
                                            <option value="Medizintechnik">Medizintechnik</option>
                                            <option value="Optik">Optik</option>
                                            <option value="Robotik">Robotik</option>
                                            <option value="Sport">Sport</option>
                                            <option value="Steuerberatung/Wirtschaftsprüfung">Steuerberatung/Wirtschaftsprüfung</option>
                                            <option value="Tourismus">Tourismus</option>
                                            <option value="Gastronomie">Gastronomie</option>
                                        </InputSelect>
                                        <div class="p-1 text-right mb-0">
                                            <button style="background: #61a48c;color: rgb(255,255,255);" type="submit" >Next<i class="oi oi-arrow-right"></i></button>
                                        </div>
                                    </EditForm>
                </div>
        </div>
    </div>
</div></div>

using System;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Components;
using Team01.Models;
using Team01.Services.Interfaces;


namespace Team01.Pages
{

    public partial class CreateProposal
    {
        private Proposal _currProposal;
        [Inject] private IProposalService ProposalService { get; set; }
        [Inject] private NavigationManager NavigationManager { get; set; }

        protected override async Task OnInitializedAsync()
        {
            _currProposal = new Proposal()
            {
                DateCreated = DateTime.Now,
            };
        }


        private async Task HandleValidSubmit()
        {
            await ProposalService.UpdateProposalAsync(_currProposal);
            NavigationManager.NavigateTo("Angebot-erstellen/skills");
        }

    }
}

With this test:

  [Test]
        public async Task CreateProposal_SuccsessfullyNavigatesToSkillPage()
        {
            using var ctx = new Bunit.TestContext();
            ctx.Services.AddSingleton<IProposalService>(_proposalService);
            var navMan = ctx.Services.GetRequiredService<NavigationManager>();

            var cut = ctx.RenderComponent<CreateProposal>();
            
            cut.Find("input").Change("TestTitle");
            cut.Find("textarea").Change("A proposal description");
            cut.Find("select").Change("Beratung");
            cut.Find("form").Submit();
           
            
            Assert.AreEqual($"{navMan.BaseUri}Angebot-erstellen/skills", navMan.Uri);
 
        }

Results in this output:

  Expected string length 41 but was 17. Strings differ at index 17.

Expected behavior: it should go to the desired link like it does within in the browser.

Version info:

• bUnit version: 1.1.5
• .NET Runtime and Blazor version: .NET5.0
• OS type and version: macOS Big Sur 11.4

Additional context: Once I add an onclick to the button and trigger the nav manager here it works as expected.

within test:

            cut.Find("form").Submit();
            cut.Find("button").Click();

            Assert.AreEqual($"{navMan.BaseUri}Angebot-erstellen/skills", navMan.Uri);

and html:

<button style="background: #61a48c;color: rgb(255,255,255);" @onclick=@(() => NavigationManager.NavigateTo("/Angebot-erstellen/skills")) type="submit" >Next<i class="oi oi-arrow-right"></i></button>