Unit Test with Async is Inconclusive with FluentAssertions and NSubstitute
<p>I'm testing this factory</p>

<pre><code>    public class ContratoFactory : IContratoFactory
    {
        private readonly IContratoPodeSerCriadoValidation _contratoPodeSerCriadoValidation;

        public ContratoFactory(IContratoPodeSerCriadoValidation contratoPodeSerCriadoValidation)
        {
            _contratoPodeSerCriadoValidation = contratoPodeSerCriadoValidation;
        }

        public async Task&lt;IValidationResult&gt; Build(Contrato entity)
        {
            try
            {
                var result = _contratoPodeSerCriadoValidation.Valid(entity);
            }
            catch (Exception ex)
            {

                // throw 
            }
        }

        public async Task AdicionarLocalBase(Contrato entity)
        {
        }
    }
</code></pre>

<p>and here is my test class</p>

<pre><code>    [TestClass]
    public class ContratoFactoryTests
    {
        private IContratoPodeSerCriadoValidation _contratoPodeSerCriadoValidation;
        private ContratoFactory _contratoFactory;

        [TestInitialize]
        public void Initialize()
        {
            _contratoPodeSerCriadoValidation = Substitute.For&lt;IContratoPodeSerCriadoValidation&gt;();
            _contratoFactory = new ContratoFactory(_contratoPodeSerCriadoValidation);
        }

        [TestMethod]
        public async Task AoSerCriadoOContratoDeveSerValidado()
        {
            var contrato = ContratoValues.ContratoComEmpresaENomeValido;
            await _contratoFactory.Build(contrato);
            _contratoPodeSerCriadoValidation.Valid(contrato).Received();
        }
    }
</code></pre>

<p>When I run my tests, the thes does not run, or return a "Inconclusive" result.</p>

<p>How can I test Async calls using NSubstitute and FluentAssertions?</p>

<p>UPDATE 19/05/16</p>

<p>I fixed the test methods to return Task instead of void and the tests throws NullReferenceExceptions</p>