I have heard a lot of nice things about BDD (Behavior Driven Development), so today I have decided to try out SpecFlow. I have downloaded and installed. Then I have created a new/empty WPF application and added a very simple calculator interface (with one sum method) and implemented.

For BDD testing I haved added a new project to my solution with a simple SpecFlow feature as follows:

Feature: Addition
In order to avoid silly mistakes
As a math idiot
I want to be told the sum of two numbers

Scenario: Add two numbers
Given a calculator
When I sum 50 and 70
Then the result should be 120

Then I have added a new class to my test project and implemented the steps for testing as follows:

[Binding]
class CalculatorSteps
{
  private readonly StandardKernel _kernel = new StandardKernel();

  private ICalculator _calc;
  private int _lastResult;

  public CalculatorSteps()
  {
    _kernel.Bind<ICalculator>().To<Calculator>();
  }

  [Given(@"a calculator")]
  public void GivenACalculator()
  {
    _calc = _kernel.Get<ICalculator>();
  }

  [When(@"I sum (\d+) and (\d+)")]
  public void WhenISum(int num1, int num2)
  {
    _lastResult = _calc.Sum(num1, num2);
  }

  [Then(@"the result should be (\d+)")]
  public void ThenTheResultShouldBe(int result)
  {
    Assert.AreEqual(result, _lastResult);
  }
}

Note: As you see I am using Ninject (StandardKernel), but there is no real advantage of using an IoC container for this task, it's just for fun and because I like to learn/study Ninject in the near future.

Finally build the solution, open the test assembly (WpfWithBdd.SpecFlow.dll) with NUnit and hit Run... producing the following output:

The output is nice and self-explanatory!

The very trivial code for this post is available here.

Hope you enjoy. See you next time.