public async Task Create()
{
var command = new CreatePartnerCommand();
_mockMediator.Setup(x => x.Send(command, It.IsAny <CancellationToken>()))
.ReturnsAsync(123);
var result = await _sut.Create(command);
Assert.IsAssignableFrom <OkObjectResult>(result.Result);
Assert.AreEqual(123, ((OkObjectResult)result.Result).Value);
}