Providing multiple When statements for SpecFlow Scenario

Question

Fairly new to SpecFlow so bear with me.

I was working with a colleague to get a basic understanding of what you can do with SpecFlow.

We were using the classic FizzBuzz problem, which we have used to test unit testing to compare how we would do a similar problem in SpecFlow.

we wrote our scenarios as follows growing the code as needed:

(please excuse naming just wanted to get the tests writ)

Scenario: 1 is 1
    Given there is a FizzBuzzFactory
    When you ask What I Am with the value of 1
    Then the answer should be 1 on the screen

Scenario: 3 is Fizz
    Given there is a FizzBuzzFactory
    When you ask What I Am with the value of 3
    Then the answer should be Fizz on the screen

Scenario: 5 is Buzz
    Given there is a FizzBuzzFactory
    When you ask What I Am with the value of 5
    Then the answer should be Buzz on the screen

Scenario: 15 is FizzBuzz
    Given there is a FizzBuzzFactory
    When you ask What I Am with the value of 15
    Then the answer should be FizzBuzz on the screen

This lead to an evolution to develop a method that would calculate a sum of some numbers

The scenario we wrote was:

Scenario: Sumof 1 + 2 + 3 is Fizz
    Given there is a FizzBuzzFactory
    When you add the sum of 1
    When you add the sum of 2
    When you add the sum of 3
    Then the answer should be Fizz on the screen

The method we wrote accepted one number at a time to then sum up.

Ideally I would provide:

Scenario: Sumof 1 + 2 + 3 in one go is Fizz
    Given there is a FizzBuzzFactory
    When you add the sum of 1,2,3
    Then the answer should be Fizz on the screen

How can you go about setting up the statement so that you can expect a params int[] on the method signature.

Answer 1

Your problem is supported really nicely by the specflow step bindings, if you use a StepArgumentTransformation. This is why I love specflow.

[When(@"you add the sum of (.*)")]
public void WhenYouAddTheSumOf(int[] p1)
{
    ScenarioContext.Current.Pending();
}

[StepArgumentTransformation(@"(\d+(?:,\d+)*)")]
public int[] IntArray(string intCsv)
{
    return intCsv.Split(',').Select(int.Parse).ToArray();
}

The StepArgumentTransformation here will allow you to take any comma separated list of ints in any step definition from now on, and accept it as an Array parameter.

It's worth learning a few regex bits if you want to play with StepArgumentTransformations, to make them nice and specific. Note I could have used (\d+(?:,\d+)*) instead of .* in the When binding too.