Combining SpecFlow table and Moq mocked object

Question

I have a situation where I want to use a mocked object (using Moq) so I can create setup and expectations, but also want to supply some of the property values using the SpecFlow Table. Is there a convenient way to create a mock and supply the table for the seed values?

// Specflow feature

Scenario Outline: MyOutline
Given I have a MyObject object as
| Field | Value     |
| Title | The Title |
| Id    | The Id    |


// Specflow step code    

Mock<MyObject> _myMock;

[Given(@"I have a MyObject object as")]
public void GivenIHaveAMyObjectObjectAs(Table table)
{
   var obj = table.CreateInstance<MyObject>();

   _myMock = new Mock<MyObject>();

   // How do I easily combine the two?

}

Answer 1

There is an overload of CreateInstance which takes a Func<T> methodToCreateTheInstance . You can use it to pass an already setup mock as the base for the speclow CreateInstance method:

[Given(@"I have a MyObject object as")]
public void GivenIHaveAMyObjectObjectAs(Table table)
{
   _myMock = new Mock<MyObject>();
   //you need to do all the setup before passing _myMock to table.CreateInstance
   _myMock.Setup(o => o.SomeProperty).Returns("someValue"); 

   var obj = table.CreateInstance<MyObject>(() => _myMock.Object);

   _myMock.VerifySet(foo => foo.Title = "The Title");
}

Answer 2

If the object wasn't mocked you would simply use the assist helpers (See https://github.com/techtalk/SpecFlow/wiki/SpecFlow-Assist-Helpers ) but since you need the call to Setup(...) then it won't work.

However you can also use StepArgumentTransformation like this

    [StepArgumentTransformation]
    public Mock<MyData> MockMyDataTransform(Table table)
    {
        MyData myData = new Mock<MyData>();
        var row = table.Rows[0];
        if (table.ContainsColumn("MyField"))
        {
            myData.Setup(x=>x.MyField).Returns(row["MyField"]);
        }
     ....
    }

and use it with

    [Given(@"something like:")]
    private void GivenSomethingLike(Mock<MyData> myData)
    ....