Cucumber-JVM Example Continued - Refactoring

In my previous post I showed you how to use Cucumber-JVM to execute a JUnit test. We’ll continue with that example in this post by refactoring the work we’ve done.

Open DepositStepDefinitons.java and notice the 2 private classes, User and Account which we added. Clearly, these are our domain objects that the real system will need, and that other scenarios would likely make use of too. So lets extract these private classes in to their own class files and make them public.

Once you create the User.java and Account.java classes, execute RunTests.java to make sure the scenario is still passing. Still passes? Great!

The next section I would like to highlight is the problem in our When step: When £100 is deposited in to the account. If this step was reused in another scenario we could potentially have a problem with the account object, it may be null, since we were initializing it in the Given step which we might not use in a new scenario. So lets refactor this part of the class so we always have a correctly initialized domain.

Like with regular JUnit steps there are hooks to allow us to run some code before and after each test, or in our case, each scenario. Cucumber has the same hooks, cucumber.annotation.Before. Refactor your class to look like this:

src/test/java/com/c0deattack/cucumberjvmtutorial/DepositStepDefinitions.java

package com.c0deattack.cucumberjvmtutorial;

import static org.junit.Assert.assertTrue;

import com.c0deattack.cucumberjvmtutorial.domain.Account;
import com.c0deattack.cucumberjvmtutorial.domain.User;

import cucumber.annotation.Before;
import cucumber.annotation.en.Given;
import cucumber.annotation.en.Then;
import cucumber.annotation.en.When;

public class DepositStepDefinitions {

	private User user;
	private Account account;

	@Before
	public void initialize() {
		if (user == null) {
			user = new User();
		}

		if (account == null) {
			account = new Account();
			user.setAccount(account);
		}
	}

	@Given("^a User has no money in their account$")
	public void a_User_has_no_money_in_their_current_account() {
	    assertTrue("The balance is not zero.", account.getBalance() == 0L);
	}

	@When("^£(\\d+) is deposited in to the account$")
	public void £_is_deposited_in_to_the_account(int amount) {
	    account.deposit(amount);
	}

	@Then("^the balance should be £(\\d+)$")
	public void the_balance_should_be_£(int expectedBalance) {
		int currentBalance = account.getBalance();
	    assertTrue("The expected balance was £100, but actually was: " + currentBalance, currentBalance == expectedBalance);
	}

}

Here, I’ve added an initialize method with a @Before annotation. This annotation will execute for every scenario, regardless of which Feature the scenario is in. What would make this better is if we can tell Cucumber to only invoke that Before hook on specific scenarios. We can actually do this, by tagging the Scenarios, and passing the same tag expression to the @Before annotation, like this:

src/test/java/com/c0deattack/cucumberjvmtutorial/DepositStepDefinitions.java

package com.c0deattack.cucumberjvmtutorial;

import static org.junit.Assert.assertTrue;

import com.c0deattack.cucumberjvmtutorial.domain.Account;
import com.c0deattack.cucumberjvmtutorial.domain.User;

import cucumber.annotation.Before;
import cucumber.annotation.en.Given;
import cucumber.annotation.en.Then;
import cucumber.annotation.en.When;

public class DepositStepDefinitions {

	private User user;
	private Account account;

	@Before(value="@UserAccounts")
	public void initialize() {
		if (user == null) {
			user = new User();
		}

		if (account == null) {
			account = new Account();
			user.setAccount(account);
		}
	}

	// rest of class....
}

src/test/resources/com/c0deattack/cucumberjvmtutorial/deposit.feature

Feature: Depositing money in to a User account

@UserAccounts
Scenario: Depositing money in to User's account should add money to the User's current balance
Given a User has no money in their account
When £100 is deposited in to the account
Then the balance should be £100

If you wanted a particular tag expression to apply to the all Scenarios within a Feature file then you can move the tag expression up to the first line of the file, before the word Feature.

This pretty much concludes the basics of refactoring your Cucumber step definitions. Some key points to remember:

• Make your steps reusable by thinking about the objects they interact with and the lifecycle of the objects
• Use the@Before/@After hooks to setup/teardown data
• Use tag expressions to specify when you want the @Before/@After hooks to be applied

Please leave a comment if you have any questions.

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