Unit Testing Invalid Model State in WebApi2

gistfile1.txt

[TestMethod]
public void WhenModelStateIsInvalidDoNotSave()
{
  var mockRepo = new Mock<IProductRepo>(); 
  mockRepo.Setup(x=>x.Save(It.IsAny<Product>());

  var ctrl = new ProductController(mockRepo.Object);
  ctrl.ModelState.AddModelError("SomeRandomProperty","SomeRandomProperty was not valid");

  var actual = ctrl.Post(new Product());

  mockRepo.Verify(x=>x.Save(It.IsAny<int>()),Times.Never);
  Assert.IsInstanceOfType(actual, typeof(InvalidModelStateResult));
}

public IHttpActionResult Post([FromBody] Product model)
{
  if(!ModelState.IsValid)
    {
       return BadRequest(ModelState);
     }
    
   ProductRepo.Save(model);
    return Ok();
}