我们如何在Blazor Bunit单元测试中调用调用StateHasChanged的方法

考虑以下Blazor组件:

@page "/"
<p id="message">@message</p>

@code {

    string message = "Hello!";

    public Task UpdateMessage(string newMessage)
    {
        message = newMessage;
        StateHasChanged();
        return Task.CompletedTask;
    }
}

Bunit测试该单元测试上述代码:

using Bunit;

namespace BlazorTest.Client.Tests
{
    public class IndexTests : TestContext
    {
        [Fact]
        public async Task MessageIsUpdated()
        {
            var component = RenderComponent<Pages.Index>();
            Assert.Equal("Hello!", component.Find("#message").TextContent);
            await component.Instance.UpdateMessage("Hello world!");
            Assert.Equal("Hello world!", component.Find("#message").TextContent);
        }
    }
}

这引发了一个异常:

 System.InvalidOperationException
 The current thread is not associated with the Dispatcher. Use InvokeAsync() to switch execution to the Dispatcher when triggering rendering or component state.

请帮我解释一下这个错误的含义,以及如何修复它,以便我可以对功能进行单元测试?