This specification outlines the setup process for a comprehensive testing environment using xUnit for unit testing, Moq and Moq.AutoMock for mocking dependencies, Coverlet for code coverage, and Mongo2Go for in-memory MongoDB testing. This environment will enable effective and isolated unit tests for Web APIs and services that interact with MongoDB. The instructions cover both command-line setup and setup using the Visual Studio 2022 User Interface.

Ensure you have the following installed:

• .NET SDK (version 8.0 or later)
• Visual Studio 2022 (or any other compatible IDE)
• MongoDB installed locally for development (optional, if Mongo2Go will always be used)

First, create a new test project in your solution using the command line:

dotnet new xunit -n Labyrinth.API.UnitTests
dotnet add Labyrinth.API.UnitTests reference Labyrinth.API

Navigate to your test project folder and install the following NuGet packages using the command line:

cd Labyrinth.API.UnitTests
dotnet add package xunit --version 2.4.1
dotnet add package Moq --version 4.16.1
dotnet add package Moq.AutoMock --version 1.4.0
dotnet add package Coverlet.Collector --version 3.1.2
dotnet add package Mongo2Go --version 2.2.29

1. Open Your Solution: Launch Visual Studio 2022 and open your existing solution or create a new one.

2. Add a New Project:

   • Right-click on your solution in the Solution Explorer.
   • Select Add > New Project.
   • In the New Project dialog, search for "xUnit Test Project".
   • Select xUnit Test Project (.NET Core) and click Next.
   • Name the project Labyrinth.API.UnitTests and click Create.
   • Choose .NET 8.0 as the target framework if prompted.

3. Reference the Main Project:

   • Right-click on the newly created Labyrinth.API.UnitTests project.
   • Select Add > Project Reference....
   • Check the box next to your main project (Labyrinth.API) and click OK.

1. Open the NuGet Package Manager:

   • Right-click on the Labyrinth.API.UnitTests project in the Solution Explorer.
   • Select Manage NuGet Packages....

2. Install Packages:

   • Go to the Browse tab and search for each of the following packages:
     • xunit
     • Moq
     • Moq.AutoMock
     • Coverlet.Collector
     • Mongo2Go
   • Select each package and click Install. Confirm any prompts to accept license agreements.

1. Edit the Project File:
   • Right-click on the Labyrinth.API.UnitTests project in Solution Explorer.
   • Select Edit Project File.
   • Add the following lines to include the Coverlet collector:

<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFramework>net8.0</TargetFramework>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="xunit" Version="2.4.1" />
<PackageReference Include="Moq" Version="4.16.1" />
<PackageReference Include="Moq.AutoMock" Version="1.4.0" />
<PackageReference Include="Coverlet.Collector" Version="3.1.2" />
<PackageReference Include="Mongo2Go" Version="2.2.29" />
</ItemGroup>
<ItemGroup>
<DotNetCliToolReference Include="coverlet" Version="3.1.2" />
</ItemGroup>
</Project>

2. Save and Close the project file.

1. Create a Helper Class:
   • Right-click on the Labyrinth.API.UnitTests project in Solution Explorer.
   • Select Add > Class....
   • Name the class MongoDbFixture.cs and click Add.
   • Implement the MongoDbFixture class as shown below:

using Mongo2Go;
using MongoDB.Driver;
public class MongoDbFixture : IDisposable
{
    public MongoDbRunner Runner { get; private set; }
    public IMongoClient Client { get; private set; }
    public IMongoDatabase Database { get; private set; }

    public MongoDbFixture()
    {
        Runner = MongoDbRunner.Start();
        Client = new MongoClient(Runner.ConnectionString);
        Database = Client.GetDatabase("LabyrinthTestDb");
    }

    public void Dispose()
    {
        Runner.Dispose();
    }
}

1. Create a Test Class:

   • Right-click on the Labyrinth.API.UnitTests project in Solution Explorer.
   • Select Add > Class....
   • Name the class CharacterServiceTests.cs and click Add.

2. Implement the Test Class:

using Xunit;
using Moq;
using Moq.AutoMock;
using Labyrinth.API.Services;
using Labyrinth.API.Entities.Characters;
using MongoDB.Driver;
using System.Threading.Tasks;

public class CharacterServiceTests : IClassFixture<MongoDbFixture>
{
    private readonly MongoDbFixture _mongoDbFixture;
    private readonly AutoMocker _mocker;
    public CharacterServiceTests(MongoDbFixture mongoDbFixture)
    {
        _mongoDbFixture = mongoDbFixture;
        _mocker = new AutoMocker();
     }

[Fact]
    public async Task CreateCharacterAsync_ShouldAddCharacterToDatabase()
    {
        // Arrange
        var characterService = _mocker.CreateInstance<CharacterService>();
        var character = new PlayerCharacter { Name = "Test Character" };

        // Act
        await characterService.CreateCharacterAsync(character.Name, CharacterClass.Warrior, Race.Human);
        var collection = _mongoDbFixture.Database.GetCollection<Character>("Characters");
        var characterFromDb = await collection.Find(c => c.Name == "Test Character").FirstOrDefaultAsync();

        // Assert
        Assert.NotNull(characterFromDb);
        Assert.Equal(character.Name, characterFromDb.Name);
    }
}

1. Run Tests:

   • Open the Test Explorer window from the View > Test Explorer menu.
   • Click the Run All button to execute all tests.

2. View Code Coverage:

   • Go to Test > Analyze Code Coverage > All Tests.
   • This will display the code coverage results in the Code Coverage Results window.
   • Review the results to understand the percentage of code covered by your tests.

3. Generate a Detailed Report (Optional):

   • For more detailed coverage reports, you can use command-line tools as described in the previous section.

• Folder Structure: Organize your test classes into folders by feature or service to improve maintainability and clarity. Right-click on the project, choose Add > New Folder, and categorize tests accordingly.
• Naming Conventions: Use descriptive names for test methods to clearly indicate what they are testing, such as MethodName_StateUnderTest_ExpectedBehavior.

• Arrange-Act-Assert Pattern: Follow this pattern consistently across all test methods to ensure clarity and maintainability.
• Mock Only What You Need: Use Moq to mock only the dependencies required for the test. Avoid over-mocking, which can make tests brittle and difficult to maintain.
• Use AutoMocker Sparingly: While Moq.AutoMock simplifies mocking setup, be mindful of its use to avoid hiding dependencies that should be explicitly declared.

Setting up a testing environment with xUnit, Moq, Moq.AutoMock, Coverlet, and Mongo2Go on .NET 8.0 provides a comprehensive foundation for testing Web APIs and MongoDB-dependent services. This environment supports high code coverage and ensures your codebase remains robust, maintainable, and reliable. By following the steps outlined in this specification, both through command-line instructions and using Visual Studio 2022 UI, you'll be well-equipped to build effective unit tests and maintain a high level of code quality throughout your development process.