How to unit test with ILogger in ASP.NET Core

Question

This is my controller:

public class BlogController : Controller
{
    private IDAO _blogDAO;
    private readonly ILogger _         


        

Answer 1

Use a custom logger that uses ITestOutputHelper (from xunit) to capture output and logs. The following is a small sample that only writes the state to the output.

public class XunitLogger : ILogger, IDisposable
{
    private ITestOutputHelper _output;

    public XunitLogger(ITestOutputHelper output)
    {
        _output = output;
    }
    public void Log(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func formatter)
    {
        _output.WriteLine(state.ToString());
    }

    public bool IsEnabled(LogLevel logLevel)
    {
        return true;
    }

    public IDisposable BeginScope(TState state)
    {
        return this;
    }

    public void Dispose()
    {
    }
}

Use it in your unittests like

public class BlogControllerTest
{
  private XunitLogger _logger;

  public BlogControllerTest(ITestOutputHelper output){
    _logger = new XunitLogger(output);
  }

  [Fact]
  public void Index_ReturnAViewResult_WithAListOfBlog()
  {
    var mockRepo = new Mock>();
    mockRepo.Setup(repo => repo.GetMany(null)).Returns(GetListBlog());
    var controller = new BlogController(_logger,mockRepo.Object);
    // rest
  }
}