In this post, App Dev Managers Robert Schumann and Ben Hlaban, introduce us to Blazor – an experimental web UI framework based on C#, Razor, and HTML that runs in the browser via WebAssembly.

This journey started from a blog by Daniel Roth. Other than the YouTube of Steve Sanderson’s prototype demo at NDC Oslo, this wasn’t much information to draw from.

A few days later I mention Blazor to my colleague Ben, and he starts asking a bunch of rapid-fire questions. Whoa! Time-out. With coffee top-offs, we start a Skype call, launch Visual Studio, git clone repo, and intrigue quickly ensued.

This blog is about getting started with Blazor. We’ll provide setup guidance, develop a cursory ToDo List application using the MVC pattern, and even do some unit testing. A second blog is intended to delve into E2E testing the application using Selenium and demonstrate how to position the project for CI/CD.

Pre-requisites*

• .NET Core SDK (>2.1.4)
• At command prompt type “dotnet --version”
• Download: https://www.microsoft.com/net/learn/get-started/windows
• Node.js (>8.3)
• At command prompt type “node -v”
• Download: https://nodejs.org/en/
• Visual Studio (>2017)
• Download: https://www.visualstudio.com/thank-you-downloading-visual-studio/?sku=Community&rel=15
• · Blazor.VSExtension.VSIX
• Download: https://github.com/SteveSanderson/Blazor/releases/download/v0.3.1/Blazor.VSExtension.vsix

* If you had to install any of the above please do cursory system reboot

Setup

• Launch Visual Studio Installer
• Make sure Visual Studio is up-to-date
• Make sure “ASP.NET and web development” is enabled
• Make sure “.NET Core cross-platform development” is enabled
• Install Blazor project template
• Double-click previously downloaded file Blazor.VSExtension.VSIX
  or
• At command via VSIXInstaller.exe Blazor.VSExtension.VSIX

Here we go…

• In Visual Studio 2017, select File | New Project | Visual Studio | Web | Blazor application
• Name this new project “HelloBlazor”. Click OK button.
• Press CTRL + F5 to make sure the default baseline project works. IIS Express should spin-up. The project eventually loads and is a typical Visual Studio templated SPA with Home, Counter, and Fetch Data features OTB.

• Right-click HelloBlazor project | Add | Class | Name = “Todo.cs” | OK

namespace HelloBlazor
{
   public class Todo
   {
      public string Description { get; set; }
      public bool IsComplete { get; set; }
   }
}

• Right-click HelloBlazor project | Add | Class | Name = “TodoComponent .cs” | OK

using Blazor.Components;
using System.Collections.Generic;
namespace HelloBlazor
{
   public class TodoComponent : RazorComponent
   {
      public IList Todos = new List();
      public Todo NewTodo = new Todo();
      public void AddTodo()
      {
         if (!string.IsNullOrWhiteSpace(NewTodo.Description))
         {
            Todos.Add(new Todo { Description = NewTodo.Description, IsComplete = NewTodo.IsComplete });
            NewTodo = new Todo();
         }
      }
   }
}

• Right-click HelloBlazor project | Add | New Item | Web | ASP.NET | Razor View | Name = “TodoList.cshtml” | OK

@using HelloBlazor
@inherits TodoComponent
Todo List (@Todos.Count(todo => !todo.IsComplete))

@foreach (var todo in Todos)

{

}

• Add

• Finally, let’s add a menu link to the new page
• Double-click or open the file Shared/NavMenu.cshtml
• Add a new list item to the existing unordered list;

. . .

• Todo List

• Press CTRL + F5 to make sure the modified project works. The new page should be available on the left navbar from the “Todo List” link.

Unit Testing

• Right-click HelloBlazor solution | Add | New Project | Installed | Visual C# | Web | .NET Core | MSTest Test Project (.NET Core) | Name = HelloBlazor.Test | OK
• Right-click Dependencies | Add Reference | Projects | Solution | HelloBlazor | OK
• Right-click UnitTest1.cs file | Rename | Name = TodoComponentTests.cs | Yes
• Within the TodoComponentTests class rename TestMethod1 to AddToDo

using Microsoft.VisualStudio.TestTools.UnitTesting;
namespace HelloBlazor.Tests
{
   [TestClass]
   public class TodoComponentTests
   {
      [TestMethod]
      public void AddTodo()
      {
         //arrange
         var todoComponent = new TodoComponent();
         var description = "this is a test";
         var isComplete = false;
         //act
         todoComponent.NewTodo.Description = description;
         todoComponent.NewTodo.IsComplete = isComplete;
         todoComponent.AddTodo();
         //assert
         Assert.IsTrue(todoComponent.Todos.Count == 1);
         Assert.IsTrue(todoComponent.Todos[0].Description == description);
         Assert.IsTrue(todoComponent.Todos[0].IsComplete == isComplete);
      }
   }
}

• Press CTRL+R,A to run all tests.

References

• Steve Sanderson’s Blog
  http://blog.stevensanderson.com/
• Microsoft ASP.NET
  https://www.asp.net/
• Blazor on Git
  https://github.com/aspnet/blazor
• Introduction to Razor Pages in ASP.NET Core
  https://docs.microsoft.com/en-us/aspnet/core/mvc/razor-pages/?tabs=visual-studio

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