Boolean parameters for SpecFlow steps

Question

In SpecFlow, I want to check for the presence of a string in a step definition and at the moment I am doing clunky things like this contrived example:

[Given(@"Foo ( bar)?")]
public void GivenFoo(string bar)
{
    if (bar == " bar")
    {
        // do bar
    }
}

However, I'd like to do something like this:

[Given(@"Foo ( bar)?")]
public void GivenFoo(bool bar)
{
    if (bar)
    {
        // do bar
    }
}

But I can't find out how, so is this possible and if so how?

Answer 1

You definitely can do that sort of thing, using a StepArgumentTransformation method. You still have to write the parser logic, but you can sequester it into a method who's only purpose is to perform that parsing.

Example feature file:

Feature: I win if I am Batman

Scenario: Happy
    Given I am the Batman
    Then I defeat the Joker

Scenario: Sad
    Given I am not the Batman
    Then I am defeated by the Joker

Specflow Bindings (C#):

[Binding]
public class IWinIfIAmBatmanFeature
{
    private bool iAmBatman;

    [StepArgumentTransformation(@"(am ?.*)")]
    public bool AmToBool(string value)
    {
        return value == "am";
    }

    [Given(@"I (.*) the Batman")]
    public void WhoAmI(bool amIBatman)
    {
        iAmBatman = amIBatman;
    }

    [StepArgumentTransformation(@"(defeat|am defeated by)")]
    public bool WinLoseToBool(string value)
    {
        return value == "defeat";
    }

    [Then(@"I (.*) the Joker")]
    public void SuccessCondition(bool value)
    {
        Assert.AreEqual(iAmBatman, value);
    }
}

The key factor is that the regex match in your Given clause is matched by the step argument transformation. So in I (.*) the Batman, if the capture matches the regex in the argument for the StepArgumentTransformation, as it does in the attribute for AmToBool then that is the transformation that gets used.