Integration Test with IOptions <> in .NET Core

Question

I pass IOption<T> to my CommandBus to get the settings from my ServiceBusSetting class. I want to perform an integration test on my bus. I don't want to allow it, just use new QueueCommandBus and you need to pass IOptions .

 var services = new ServiceCollection().AddOptions(); services.Configure<ServiceBusAppSettings>(Configuration.GetSection("ServiceBus")); var options = services.BuildServiceProvider().GetService<IOptions<ServiceBusAppSettings>>(); ////Act var commandBus = new QueueCommandBus(options); 

This works fine, but it feels very complex code to get IOptions<T> from my appsetting.json in my test project.

Any clue if this is the only way or is there a better way?

Answer 1

You do not need to create a ServiceCollection or IServiceProvider . The IConfiguration interface has a Bind() method either with .NET Core 1.1 and Get<T> , which can be used to directly obtain a strongly typed object:

 var config = Configuration.GetSection("ServiceBus"); // .NET Core 1.0 var options = new ServiceBusAppSettings(); config.Bind(options); // .NET Core 1.1 var options = config.Get<ServiceBusAppSettings>(); 

I like to add them as static methods to my AppSettings strongly typed object so that it is convenient to load them from JSON both in my web application and in unit tests.

AppSettings.cs:

 using System; using System.Collections.Generic; using System.Linq; using System.Threading.Tasks; using Microsoft.Extensions.Configuration; namespace My.Namespace { public class AppSettings { public class ServiceBusAppSettings { public string Setting1; public int Setting2; } public class ApiSettings { public bool FormatJson { get; set; } } public class MySqlSettings { public string User { get; set; } public string Password { get; set; } public string Host { get; set; } public string Database { get; set; } public int Port { get; set; } = 3306; public string GetConnectionString() { return $"Server={Host};Database={Database};Port={Port};Uid={User};Pwd={Password}"; } } public ServiceBusAppSettings ServiceBus { get; set; } = new ServiceBusAppSettings(); public ApiSettings Api { get; set; } = new ApiSettings(); public MySqlSettings MySql { get; set; } = new MySqlSettings(); // Static load helper methods. These could also be moved to a factory class. public static IConfigurationRoot GetConfiguration(string dir) { return GetConfiguration(dir, null); } public static IConfigurationRoot GetConfiguration(string dir, string environmentName) { if (string.IsNullOrEmpty(environmentName)) environmentName = "Development"; var builder = new ConfigurationBuilder() .SetBasePath(dir) .AddJsonFile("appsettings.json", true, true) .AddJsonFile($"appsettings.{environmentName}.json", true) .AddEnvironmentVariables(); return builder.Build(); } public static AppSettings GetSettings(string dir) { return GetSettings(dir, null); } public static AppSettings GetSettings(string dir, string environmentName) { var config = GetConfiguration(dir, environmentName); return GetSettings(config); } public static AppSettings GetSettings(IConfiguration config) { return config.Get<AppSettings>(); } } } 

Kernel ASP.NET Core Startup.cs : (Getting a custom settings object often helps at this point when setting up other services ...)

 public class Startup { public Startup(IHostingEnvironment env) { Configuration = AppSettings.GetConfiguration(env.ContentRootPath, env.EnvironmentName); } public IConfigurationRoot Configuration { get; } // This method gets called by the runtime. Use this method to add services to the container. public void ConfigureServices(IServiceCollection services) { // Configure the service collection. services.AddOptions(); services.Configure<AppSettings>(Configuration); // It can also be handy to get the AppSettings object here. var settings = AppSettings.GetSettings(Configuration); // Add framework services. services.AddMvc() .AddJsonOptions(options => { options.SerializerSettings.ContractResolver = new DefaultContractResolver(); // Pretty-print JSON in Development options.SerializerSettings.Formatting = settings.Api.FormatJson ? Formatting.Indented : Formatting.None; }); // Store DB connection info in AppSettings too... var conn = settings.MySql.GetConnectionString(); services.AddDbContext<MyDbContext>(opt => opt.UseMySql(conn)); } } 

In the test class:

 var testDir = AppContext.BaseDirectory; var settings = AppSettings.GetSettings(testDir, "Test"); //Act var commandBus = new QueueCommandBus(settings);