In this article, you will learn how to functional test a dotnet core Web API project with an SQL database using Visual Studio and xUnit.

Source code on GitHub

Prerequisites

The following prerequisites will be required to complete this tutorial:

• Visual Studio 2022 Community with the ASP.NET and web development workload installed. If you don't have Visual Studio installed, download Visual Studio for free before you begin.
• A dotnet core Web API project. If you don't have a project you can follow the first step in these instructions to create one.

Add a Functional Test Project to an existing Solution

1. Open a dotnet core Web API project in Visual Studio.

2. Right click on the Solution, and then select Add > New Project....

   

3. Search for xunit, and then select xUnit Test Project, and then select Next.

   

4. Enter the following values in the Configure your new project window, and then select Next.

   Parameter	Value
   Project Name	Monitored.FunctionalTests
   Location	Location of your choice

   

5. Enter the following values in Additional information, and then select Create.

   Parameter	Value
   Framework	.NET 6.0 (Long-term support)

   

Install Web API Testing nuget packages

1. In Visual Studio, select Tools > Nuget Package Manager > Package Manager Console.

   

2. Enter the following.

   Install-Package Microsoft.AspNetCore.Mvc.Testing -Version 6.0.14
   

Add a Basic Functional Test

Expose the Web Api Project to the Test Project

1. Add the following code to the program.cs class after app.Run in the Web Api project.

   public partial class Program { }
   

Reference the Web API Project in the Test Project

1. Right click on the Test Project, and then select Add > Project Reference....

   

2. Tick the Web API Project, and then select OK.

   

Add a Custom WebApplicationFactory to the Test Project

1. In the test project, add the following class CustomWebApplicationFactory into a new Base folder, replacing {YourConnectionString} with your connection string.

   public class CustomWebApplicationFactory<TProgram>
       : WebApplicationFactory<TProgram> where TProgram : class
   {
       protected override void ConfigureWebHost(IWebHostBuilder builder)
       {
           builder.ConfigureServices(services =>
           {
               var dbContextDescriptor = services.SingleOrDefault(
                   d => d.ServiceType ==
                       typeof(DbContextOptions<MonitoredAPIDataContext>));
   
               services.Remove(dbContextDescriptor);
   
               var dbConnectionDescriptor = services.SingleOrDefault(
                   d => d.ServiceType ==
                       typeof(DbConnection));
   
               services.Remove(dbConnectionDescriptor);
   
               // Create open SqlConnection so EF won't automatically close it.
               services.AddSingleton<DbConnection>(container =>
               {
                   var connection = new SqlConnection("{YourConnectionString}");
                   connection.Open();
   
                   return connection;
               });
   
               services.AddDbContext<MonitoredAPIDataContext>((container, options) =>
               {
                   var connection = container.GetRequiredService<DbConnection>();
                   options.UseSqlServer(connection);
               });
           });
   
           builder.UseEnvironment("Development");
       }
   }
   

2. Add the following class WeatherForecastScenarios into the root of the test project.

   public class WeatherForecastScenarios : IClassFixture<CustomWebApplicationFactory<Program>>
   {
       private readonly HttpClient _client;
       private readonly CustomWebApplicationFactory<Program> _factory;
       public WeatherForecastScenarios(CustomWebApplicationFactory<Program> factory)
       {
           _factory = factory;
           _client = factory.CreateClient(new WebApplicationFactoryClientOptions
           {
               AllowAutoRedirect = false
           });
       }
   
       [Fact]
       public async Task Get_get_filtered_weather_forecasts_and_response_ok_status_code()
       {
           // Act
           var response = await _client.GetAsync("WeatherForecast?take=10&skip=0");
   
           // Assert
           response.EnsureSuccessStatusCode();
       }
   
   }
   

3. The final test project should look like the following.

   

Run Functional Tests

1. In Visual Studio, select Test, and then Test Explorer.

   

2. In the Test Explorer, select the button.

   

3. Once the tests have run, you will see that all tests pass.