.NET Core Unit Testing - Mock IOptions

Question

I feel like I\'m missing something really obvious here. I have classes that require injecting of options using the .NET Core IOptions pattern(?). When I unit te

Answer 1

You need to manually create and populate an IOptions<SampleOptions> object. You can do so via the Microsoft.Extensions.Options.Options helper class. For example:

IOptions<SampleOptions> someOptions = Options.Create<SampleOptions>(new SampleOptions());

You can simplify that a bit to:

var someOptions = Options.Create(new SampleOptions());

Obviously this isn't very useful as is. You'll need to actually create and populate a SampleOptions object and pass that into the Create method.

Answer 2

You can always create your options via Options.Create() and than simply use AutoMocker.Use(options) before actually creating the mocked instance of the repository you're testing. Using AutoMocker.CreateInstance<>() makes it easier to create instances without manually passing parameters

I've changed you're SampleRepo a bit in order to be able to reproduce the behavior I think you want to achieve.

public class SampleRepoTests
{
    private readonly AutoMocker _mocker = new AutoMocker();
    private readonly ISampleRepo _sampleRepo;

    private readonly IOptions<SampleOptions> _options = Options.Create(new SampleOptions()
        {FirstSetting = "firstSetting"});

    public SampleRepoTests()
    {
        _mocker.Use(_options);
        _sampleRepo = _mocker.CreateInstance<SampleRepo>();
    }

    [Fact]
    public void Test_Options_Injected()
    {
        var firstSetting = _sampleRepo.GetFirstSetting();
        Assert.True(firstSetting == "firstSetting");
    }
}

public class SampleRepo : ISampleRepo
{
    private SampleOptions _options;

    public SampleRepo(IOptions<SampleOptions> options)
    {
        _options = options.Value;
    }

    public string GetFirstSetting()
    {
        return _options.FirstSetting;
    }
}

public interface ISampleRepo
{
    string GetFirstSetting();
}

public class SampleOptions
{
    public string FirstSetting { get; set; }
}