Modern application frameworks like Spring promote a POJO-based programming model, and POJOs are inherently easy to unit test. But how can we effectively integration test our application outside the container while still getting as close to a production-like environment as possible? This session will show attendees how to approximate a target production environment using the Spring TestContext Framework to drive fast, repeatable, "out-of-container" integration tests. To simulate a live system, the session will cover open source integration testing techniques such as the use of in-memory databases, JMS providers, and Servlet containers as well as mock SMTP and FTP servers.

1. Effective out-of-container
Integration Testing
Sam Brannen
Swi+mind GmbH

2. Speaker Profile
• Senior So+ware Consultant – Swi+mind GmbH
• Java developer with 13+ years' experience
• Spring Framework Core Developer
– Author of the Spring TestContext Framework
• Previous SpringSource dm Server™ developer
• Regular speaker at conferences on Spring, dm
Server, Java, OSGi, and tesOng
• Lead author of Spring in a Nutshell;
chief technical reviewer for Spring Recipes

3. Agenda
• Background
• Goals of IntegraOon TesOng
• The Challenge
• Proposed SoluOon
• DI and IoC as Enablers
• SimulaOng a ProducOon Environment
• Spring TestContext Framework
• Q&A

4. Background

5. Types of Tests
• unit tests
• integraOon tests
– component interacOon: mulOple units
– cross‐process interacOon: database, mail, etc.
• system tests
– end‐to‐end tesOng with live systems
• user acceptance tests

6. Unit Tests
• are simple to set up
• use dynamic mocks or stubs for dependencies
• instanOate the SUT and test it
• run fast
• but only test a single unit

7. IntegraOon Tests
• test interacOons between mulOple
components
• relaOvely easy to set up without external
system dependencies
• challenging to set up with external system
dependencies
• more challenging when/if applicaOon code
depends on the container

8. Modern Enterprise Java ApplicaOons
• Integrate with external systems
– SMTP, FTP, LDAP, RDBMS, Web Services, JMS
• Rely on container‐provided funcOonality
– data sources, connecOon factories, transacOon
manager

9. Goals of Integra3on Tes3ng

10. EffecOve IntegraOon TesOng
• Fast
• Repeatable
• Automated
• Easy to configure
• Provide good code coverage of end‐to‐end
business use cases

11. Out‐of‐container
• Zero reliance on availability of external
systems
• Can be run anywhere
– developer workstaOon
– CI server
• Approximate a target producOon environment

12. The Challenge

13. How can we effec9vely integraOon test an
enterprise Java applicaOon...
outside the container...
while sOll ge_ng as close as possible to a
producOon‐like environment?

14. Proposed Solu3on

15. Approximate the producOon
environment by...
• Using open source libraries and frameworks to
simulate
– a single external system dependency, or
– mulOple external system dependencies
• Using the Spring TestContext Framework to
drive fast, out‐of‐container integraOon tests
– with simulated external systems started in‐
memory

16. DI and IoC as Enablers
Dependency Injec9on and Inversion of Control
collec9vely decouple applica9on code from the
deployment environment.

17. DI and IoC Increase Testability
• Dependencies are injected, not explicitly
instanOated
– Not only for applicaOon components, but also for
infrastructure components
• JNDI look‐ups for container provided resources
– EJBs, data sources, connecOon factories, etc.
• Programming to interfaces
– Allows us to transparently swap implementaOons

18. Simula3ng a Produc3on Environment

19. Step 1
• Ensure your applicaOon configuraOon can be
split into:
– applicaOon‐specific configuraOon
• business logic
• service layer, repository layer, etc.
– environment‐specific configuraOon
• infrastructure

20. Step 2
• Ensure environment‐specific components can
be easily overridden in test configuraOon – for
example, by using well defined bean IDs.
– DataSource: dataSource
– PladormTransacOonManager:
transac9onManager
– JMS ConnecOonFactory: connec9onFactory

21. Step 3
• Use open source replacements for
environment‐specific components
– preferably configurable via Spring
ApplicaOonContext
– typically in‐memory (a.k.a., embedded mode)

22. Open Source Frameworks for
Embedded Use

23. Database
• Use an in‐memory database such as
– HSQL, H2, or Derby
• Spring 3.0 provides explicit support for
– Embedded databases
– PopulaOng exisOng databases

24. Embedded Database in XML
<jdbc:embedded-database id="dataSource" type="H2">
<jdbc:script location="classpath:/my-schema.sql" />
<jdbc:script location="classpath:/my-data.sql" />
</jdbc:embedded-database>
Or simply…
<jdbc:embedded-database id="dataSource" />

25. Embedded Database in Code
private EmbeddedDatabase db;
@Before public void launchDatabase() {
db = new EmbeddedDatabaseBuilder()
.addDefaultScripts()
.build();
}
// tests …
@After public void shutdownDatabase()
{
db.shutdown();
}

26. Populate Database in XML
<jdbc:initialize-database data-source="dataSource">
<jdbc:script location="classpath:/schema_01.sql" />
<jdbc:script location="classpath:/schema_02.sql" />
<jdbc:script location="classpath:/data_01.sql" />
<jdbc:script location="classpath:/data_02.sql" />
</jdbc:initialize-database>

27. JMS
• Use an in‐memory message broker such as
AcOveMQ
• AcOveMQ can be easily configured in a Spring
ApplicaOonContext
• Versions > 4.1 even provide an <amq /> XML
namespace for DSL‐like configuraOon

28. AcOveMQ Spring ConfiguraOon
<bean id="connectionFactory" class=
"org.apache.activemq.spring.ActiveMQConnectionFactory”
p:brokerURL="vm://localhost?broker.persistent=false" />
<bean id="jmsTemplate"
class="org.springframework.jms.core.JmsTemplate"
p:connectionFactory-ref="connectionFactory" />

29. SMTP Server
• Use Dumbster's SimpleSmtpServer
– Configurable port number
– Tracks all mails sent
– Provides methods for retrieving
• Number of mails sent
• Individual mails
• Mail headers
• Mail body

30. AbstractEmailSenderTest (1/2)
public abstract class AbstractEmailSenderTest {
protected SimpleSmtpServer server;
@Before public void startSmtpServer() {
server = SimpleSmtpServer.start(getSmtpPort());
}
@After public void stopSmtpServer() {
server.stop();
}
protected abstract int getSmtpPort();

31. AbstractEmailSenderTest (2/2)
protected void assertNumEmailsSent(SimpleSmtpServer server,
int expected) {
assertEquals("Verifying number of e-mails sent.”,
expected, server.getReceivedEmailSize());
}
protected void assertEmailHeaderValue(SmtpMessage email,
String header, String expected) {
assertEquals(expected, email.getHeaderValue(header));
}
protected void assertEmailBodyContains(SmtpMessage email,
String expected) {
assertTrue(email.getBody().contains(expected));
}

32. PlainEmailSenderTest (1/2)
@ContextConfiguration("/applicationContext.xml")
public class PlainEmailSenderTest extends
AbstractEmailSenderTest {
@Autowired
private PlainEmailSenderImpl plainEmailSender;
@Override
protected int getSmtpPort() {
return 62525;
}

33. PlainEmailSenderTest (2/2)
@Test
public void plainEmail() throws Exception {
plainEmailSender.sendSimpleEmail(recipientEmail);
assertNumEmailsSent(server, 1);
SmtpMessage email =
(SmtpMessage) server.getReceivedEmail().next();
assertEmailHeaderValue(email, "Subject", "testing");
assertEmailHeaderValue(email, "From", "foo@bar.com");
assertEmailBodyContains(email, "This is a test email");
}

34. FTP Server
• Use MockFtpServer's
– FakeFtpServer
• Virtual or in‐memory file system
• User accounts and permissions
– StubFtpServer
• Low‐level FTP server commands

35. Servlet Container
• Use Jeny or Tomcat in embedded mode
• Configure Jeny with Maven and execute the
jeny:run goal

36. ConfiguraOon Tips
• Externalize connecOon se_ngs in Java
ProperOes files
• Define different ProperOes files for producOon
and tesOng
• Use Spring's PropertyPlaceholderConfigurer or
<context:property‐placeholder> for property
replacement

37. Avoid Hostname & Port Collisions
• Pay special anenOon to hostnames and ports
– SMTP
– FTP
– Servlet container
• Consider using something like Spring's
FreePortScanner

38. Demo
Embedded HSQL database with
Spring’s <jdbc /> namespace
HibernateEventRepositoryTests

39. Demo
JMS with an in‐memory AcOveMQ
message broker
JmsNamespaceTest

40. Demo
Email with Dumbster’s
SimpleSmtpServer
PlainEmailSenderTest

41. Demo
Embedded Jeny Servlet container
AbstractJeKyTest

42. Further Resources
• HSQLDB
– hnp://hsqldb.org
• H2
– hnp://www.h2database.com
• AcOveMQ
– hnp://acOvemq.apache.org
• Dumbster
– hnp://quintanaso+.com/dumbster
• MockFtpServer
– hnp://mock+pserver.sourceforge.net
• Jeny
– hnp://jeny.codehaus.org
• Tomcat
– hnp://tomcat.apache.org

43. Q&A
Sam Brannen
sam.brannen [at] swi+mind [dot] com
hnp://www.swi+mind.com
hnp://twiner.com/sam_brannen
“Spring in a Nutshell”
hnp://oreilly.com/catalog/9780596801946
available from O’Reilly in 2011