Step Definitions

The bindings (step definitions, hooks, etc.) provide the connection between the free-text specification and the application interfaces (see Bindings). For better reusability, the step definitions can be parametrized. This means that it is not necessary to define a new step definition for each step that just differs in a small portion. E.g. the steps When I perform a simple search on 'Domain' and When I perform a simple search on 'Communication' can be automated with a single step definition.

The following example shows a simple step definition that matches to the step When I perform a simple search on 'Domain' mentioned earlier.

[When(@"I perform a simple search on '(.*)'")]
public void WhenIPerformASimpleSearchOn(string searchTerm)
{
    var controller = new CatalogController();
    actionResult = controller.Search(searchTerm);
}

Here the method is annotated with the [When] attribute, providing the regular expression to be used to match the step text. The match groups ((…)) of the regular expression define the parameters for the method.

##Supported Step Definition Attributes

• [Given(regex)] - TechTalk.SpecFlow.GivenAttribute
• [When(regex)] - TechTalk.SpecFlow.WhenAttribute
• [Then(regex)] - TechTalk.SpecFlow.ThenAttribute
• [StepDefinition(regex)] - TechTalk.SpecFlow.StepDefinitionAttribute, matches for given, when or then attributes (from v1.8)

You can annotate a single method with multiple attributes in order to support different phrasings in the feature file for the same automation logic.

##Rules for the Step Definition Method

• Must be in a public class, marked with the [Binding] attribute.
• Must be a public method.
• Can be either a static or an instance method. If it is an instance method, the containing class will be instantiated once for every scenario.
• Cannot have out or ref parameters.
• Cannot have a return type.

##Regular Expression Matching Rules

• The regular expressions are always matching to the entire step text even if you not use the ^ and $ markers.
• The match groups ((…)) of the regular expression define the arguments for the method based on the order (the match result of the first group becomes the first argument, etc.).
• You can use non-capturing groups (?:regex) in order to use groups without a method argument.

##Table or Multi-line Text Arguments

If the step definition method should match for steps having table or multi-line text arguments, additional Table and/or string parameters have to be defined in the method signature to be able to receive the these arguments. If both table and multi-line text argument is used for the step, the multi-line text argument is provided first.

Given the following books
  |Author        |Title                          |
  |Martin Fowler |Analysis Patterns              |
  |Gojko Adzic   |Bridging the Communication Gap |

[Given(@"the following books")]
public void GivenTheFollowingBooks(Table table)
{
  ...
}

##See also

• Step Argument Conversions
• Scoped Bindings