Lambda Expression support for Cucumber Java8

Lambda Expression support for Cucumber-Java8

• Release Version : 0.0.20
• As we all know, with the new Cucumber-Java8 API, we can write our step definitions with lambda expressions. So cucumbe-eclipse plugin is also enhanced to support both Content-Assistance and Glue-code features for Lambda Expressions.

Features supported for Lambda Expression:

• Content-Assistance populates all steps used in lambda expressions.
• Matching of Glue-code for lambda-expression-steps in a feature file
• Pressing 'F3' key on steps in feature file redirects to the corresponding lambda-expression steps.

Test Environment:

• JDK/JRE-8
• Eclipse Java EE IDE for Web Developers. Version: Mars.2 Release (4.5.2) Build id: 20160218-0600

What is Lambda-Expression?

• A lambda expression is an anonymous function and nameless. Means by Lambda Expression we can create a Java function without any name and belonging to any class. See the below step definition. The Lambda expression is passed as a parameter in Given method. By introducing Lambda expression in Java 8, Java language has stepped into functional programming.

How to use Lambda Expression for Step-definitions?

• As lambda-expression supported by java8, You must have to use eclipse with JDK/JRE-8 version.
• If you want to write any step-definitons by lambda-expression, You must have to import cucumber-java8 api(ex.cucumber.api.java8.En) in your step-definition(java) file.
• You may wrtie step-definitions by using lambda-expression with both constructors and methods.
• All lambda-expression-steps can be populated in feature-file by Content-Assistance features
• Always use 'Ctrl+shift+o' to avoid unused import statements in your step-definition(java) file.

Sample Cucumber-Java8 Lambda Expression:

package foo;

import cucumber.api.java8.En;

public class TestLambdaStepdefs implements En {

    //Lambda-steps inside Constructors
    public TestLambdaStepdefs() {
        Given("I have (\\d+) cukes in my belly", (Integer cukes) -> {
            System.out.format("Cukes: %n\n", cukes);
        });
		
	Then("I have a some step definition", () -> {
             throw new Exception();
        });	
		
	Given("testlambda", () -> {
	     System.out.println("Inside Given");
	});

	When("^the search phrase \"([^\"]*)\" is entered$", (String phrase) -> {
		System.out.println("Inside When");
	});

	Then("^results for \"([^\"]*)\" are shown$", (String phrase) -> {
		System.out.println("Inside Then");
	});
    }
	
  //Lambda-steps inside method
  private void testLambdaSteps() {
        Before((Scenario scenario) -> {
            log.info("Before scenario : " + scenario.getName());
        });

        After((Scenario scenario) -> {
            log.info("After scenario : " + scenario.getName());
        });

        Given("^this pre condition$", () -> {
            testContext.put("some-key", "some-value");
        });

        When("^I do this$", () -> {
        });

        When("^I do that$", () -> {
        });

        Then("^I can verify that$", () -> {
            assert (testContext.get("some-key").get().equals("some-value"));
        });

        Then("^I can also verify that$", () -> {
        });
    }
}

Do Not :

• Don't try cucumber-java8-lambda-expression-steps in JDK/JRE-7 enviromnent, else it would be error in loading of Feature files in eclipse editor.
• Don't try to import cucumber-java8 api(ex.cucumber.api.java8.En) in your step-definition(java) file for JDK/JRE-7 enviromnent, else it would be error in loading of Feature files in eclipse editor.