The framework encourages a layered architecture, which implies a layered approach to testing. Now that we have a presentation layer up and running, we can look at interacting with the business layer. Unit tests are a great way to explore how a software component works. How can unit tests do interact with the database? How can a test show us how to find an account or add a new account?

Presentation - JUnit Jumpstart

Why do we test applications? How do we test applications? Why do we need a testing framework? How do we get started with JUnit?

We explore the industry-standard testing framework, JUnit.

• Writing simple tests by hand
• Writing better tests with JUnit
• Installing JUnit and running tests

Workshop - Retain

Story: MailReader profiles and subscriptions are stored for later retrieval.

• Create unit tests for business code
• Learn how to use the business code API

Prerequisites

• TestCase
  • setUp
• assertNull, assertNotNull, assertSame

New Dependencies

• Collections
• Digester
• BeanUtils
• Mailreader DAO

Exercises

• Continue using your own solution or create a new module using the "hello" solution on the CD.
• Review the Retain use case.
• Create a RetainTest case that exercises the database methods shown in the Retain Narrative.

Hint Code

Here's a setUp method and a test for the first statement.

import junit.framework.TestCase;
import org.apache.struts.apps.mailreader.dao.User;
import org.apache.struts.apps.mailreader.dao.UserDatabase;
import org.apache.struts.apps.mailreader.dao.impl.memory.MemoryUserDatabase;

public class RetainTest extends TestCase {

    protected UserDatabase userDatabase;
    protected String testName = "test-database.xml";

    public void setUp() throws Exception {
        super.setUp();
        MemoryUserDatabase memoryUserDatabase = new MemoryUserDatabase();
        memoryUserDatabase.setPathname(testName);
        userDatabase = memoryUserDatabase;
    }

    public void testDatabaseClean() throws Exception {
        User user = userDatabase.findUser("user");
        assertNull("Expected user to be created",user);
    }
   
    //  Add your test methods here. 
    //  The setUp method will run between each test. 
}

Here's the syntax for some key assertions:

assertNull("Expected user to be created", user);

assertNotNull(user);

assertSame("Expected users to match", user1, user2);

Accomplishments

• Created unit tests for business code
• Learned how to use the business code API

Extra Credit

• Read the database back after saving it and confirm that the save persisted your changes.
• Write tests to confirm failures like "User not found" and "Subscription not found"
• Write a test that creates ten users and verify each was created