.NET Core–Using IOptions<> in your unit test

An easy and typesafe way to use configuration values in your .NET core applications is through IOptions<T>.

This allows you to create a settings section in your appsettings.json:

	{
	"MySettings": {
	"ApplicationName": "SampleApp",
	"Environment": "Test"
	}
	}

view raw appsettings.json hosted with ❤ by GitHub

And then map this to a specific class:

	public class MySettings
	{
	public string ApplicationName{get;set;}
	public string Environment{get;set;}
	}

view raw MySettings.cs hosted with ❤ by GitHub

The only thing you need to do is to specify the section in your Startup.cs:

	public void ConfigureServices(IServiceCollection services)
	{
	services.Configure<MySettings>(Configuration.GetSection("MySettings"));
	}

view raw Startup.cs hosted with ❤ by GitHub

Now you can inject these settings in your code through IOptions<T>:

	public class ExampleRepository : IExampleRepository
	{
	private readonly MySettings _mySettings;
	public ExampleRepository(IOptions<MySettings> options)
	{
	_mySettings = options.Value;
	}
	}

view raw ExampleRepository.cs hosted with ❤ by GitHub

But what if you want to unit test this class? How can you create an IOptions<T> instance?

A solution exists through the Options.Create() method:

	var mySettings = Options.Create(new MySettings
	{
	ApplicationName = "Example App",
	Environment = "test"
	});
	var exampleRepository = new ExampleRepository(mySettings);

view raw OptionsCreate.cs hosted with ❤ by GitHub