Net Core: Execute All Dependency Injection in Xunit Test for AppService, Repository, etc

Question

I am trying to implement Dependency Injection in Xunit test for AppService. Ideal goal is to run the original application program Startup/configuration, and use any depende

Answer 1

Use Custom Web Application Factory and ServiceProvider.GetRequiredService below, feel free to edit and optimize the answer

CustomWebApplicationFactory:

public class CustomWebApplicationFactory : WebApplicationFactory where TStartup : class
{
    protected override void ConfigureWebHost(IWebHostBuilder builder)
    {
        builder.ConfigureAppConfiguration((hostingContext, configurationBuilder) =>
        {
            var type = typeof(TStartup);
            var path = @"C:\\OriginalApplication";

            configurationBuilder.AddJsonFile($"{path}\\appsettings.json", optional: true, reloadOnChange: true);
            configurationBuilder.AddEnvironmentVariables();
        });

        // if you want to override Physical database with in-memory database
        builder.ConfigureServices(services =>
        {
            var serviceProvider = new ServiceCollection()
                .AddEntityFrameworkInMemoryDatabase()
                .BuildServiceProvider();

            services.AddDbContext(options =>
            {
                options.UseInMemoryDatabase("DBInMemoryTest");
                options.UseInternalServiceProvider(serviceProvider);
            });
        });
    }
}

Integration Test:

public class DepartmentAppServiceTest : IClassFixture>
{
    public CustomWebApplicationFactory _factory;
    public DepartmentAppServiceTest(CustomWebApplicationFactory factory)
    {
        _factory = factory;
        _factory.CreateClient();
    }

    [Fact]
    public async Task ValidateDepartmentAppService()
    {      
        using (var scope = _factory.Server.Host.Services.CreateScope())
        {
            var departmentAppService = scope.ServiceProvider.GetRequiredService();
            var dbtest = scope.ServiceProvider.GetRequiredService();
            dbtest.Department.Add(new Department { DepartmentId = 2, DepartmentCode = "123", DepartmentName = "ABC" });
            dbtest.SaveChanges();
            var departmentDto = await departmentAppService.GetDepartmentById(2);
            Assert.Equal("123", departmentDto.DepartmentCode);
        }
    }
}

Resources:

https://docs.microsoft.com/en-us/aspnet/core/test/integration-tests?view=aspnetcore-2.2

https://fullstackmark.com/post/20/painless-integration-testing-with-aspnet-core-web-api