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Retain-Notes
Added by Ted Husted, last edited by Ted Husted on Dec 05, 2007  (view change)
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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

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