Years after Kent Beck provided JUnit, unit testing is part of most developer teams tooling. However, there’s a trend that tends to threaten unit testing, claiming only integration testing can truly detects defects in software. In this talk, we will first define what unit testing and integration testing are, and their respective pros, cons and uses. Then, we will have a look at the unique challenges posed by integration testing. Finally, tools and techniques will be presented to somewhat remedy to that so that integration testing becomes a true asset in each software developer bag of tricks.

1. @nicolas_frankel
INTEGRATION TESTING
FROM THE TRENCHES
Rebooted

2. @nicolas_frankel
ME, MYSELF AND I
● Developer
● Developer advocate

3. @nicolas_frankel
European alternative to the “big” cloud-computing
players
● Privacy-minded
● Great support

4. @nicolas_frankel
FROM THE BOOK

5. @nicolas_frankel
INTRODUCTION
INTEGRATION TESTING FROM THE TRENCHES - REBOOTED

6. @nicolas_frankel
TESTING?
● Unit Testing
● Mutation Testing
● GUI Testing
● Performance Testing
○ Load Testing
○ Stress Testing
● Endurance Testing
● Security Testing
● etc.

7. @nicolas_frankel
UNIT VS. INTEGRATION TESTING
● Unit Testing
○ Testing a unit in isolation
● Integration Testing
○ Testing the collaboration
of multiple units

8. @nicolas_frankel
EXAMPLE
● A prototype car

9. @nicolas_frankel
UNIT TESTING
● Akin to testing each nut
and bolt separately

10. @nicolas_frankel
INTEGRATION TESTING
● Akin to going on a test
drive

11. @nicolas_frankel
UNIT + INTEGRATION TESTING
● Take a prototype car on a test
drive having tested only nuts and
bolts?
● Manufacture a car having tested
nuts and bolts but without having
tested it on numerous test
drives?

12. @nicolas_frankel
SYSTEM UNDER TEST
● SUT is what get tested
● Techniques from Unit
Testing can be re-used
○ Dependency Injection
○ Test doubles

13. @nicolas_frankel
REMINDER: TEST DOUBLES
● Dummy
● Mock
● Stub
● Spy
● Fake

14. @nicolas_frankel
TESTING IS ABOUT ROI
● The larger the SUT
○ The more fragile the
test
○ The less maintainable
the test
○ The less the ROI

15. @nicolas_frankel
TESTING IS ABOUT ROI
● Tests have to be organized
in a certain way
○ The bigger the SUT
○ The less the number of
tests

16. @nicolas_frankel
TESTING IS ABOUT ROI
● Integration Testing
○ Test nominal cases

17. @nicolas_frankel
INTEGRATION
TESTING
CHALLENGES
INTEGRATION TESTING FROM THE TRENCHES - REBOOTED

18. @nicolas_frankel
INTEGRATION TESTS CHALLENGES
● Slow
● Fragile
● Hard to diagnose
https://leanpub.com/integrationtest/

19. @nicolas_frankel
Y U SLOW?
● Uses infrastructure
resources
● Uses container

20. @nicolas_frankel
COPING WITH SLOWNESS
➢Separate Integration Tests
from Unit Tests

21. @nicolas_frankel
INTEGRATION TESTS ARE STILL SLOW
● Separating IT doesn’t make
them faster
● But errors can be
uncovered faster
○ Fail fast
○ It will speed testing

22. @nicolas_frankel
HOW TO SEPARATE?
● Depends on the build tool
○ Ant
○ Maven
○ Gradle
○ Something else?

23. @nicolas_frankel
REMINDER: MAVEN LIFECYCLE

24. @nicolas_frankel
MAVEN SUREFIRE PLUGIN
● Bound to the test phase
● Runs by default
○ *Test
○ Test*
○ *TestCase

25. @nicolas_frankel
MAVEN FAILSAFE PLUGIN
● “Copy” of Surefire
● Different defaults
○ *IT
○ IT*
○ *ITCase

26. @nicolas_frankel
MAVEN FAILSAFE PLUGIN
● One goal per lifecycle phase
○ pre-integration-test
○ integration-test
○ post-integration-test
○ verify
● Must be bound explicitly

27. @nicolas_frankel
POM SNIPPET
<plugin>
<artifactId>maven-failsafe-plugin</artifactId>
<version>2.17</version>
<executions>
<execution>
<id>integration-test</id>
<goals>
<goal>integration-test</goal>
</goals>
<phase>integration-test</phase>
</execution>
<execution>
<id>verify</id>
<goals>
<goal>verify</goal>
</goals>
<phase>verify</phase>
</execution>
</executions>
</plugin>

28. @nicolas_frankel
CONTINUOUS INTEGRATION
● Unit Tests run at each commit
● Integration Tests run
“regularly”
○ Daily
○ Hourly
○ Depends on the context

29. @nicolas_frankel
Y U FRAGILE?
● Usage of infrastructure
resources
○ External
○ Multiple

30. @nicolas_frankel
INFRASTRUCTURE RESOURCES
● File system
● Time
● Databases
● Web Services
● Mail servers
● FTP Servers
● etc.

31. @nicolas_frankel
TIME/FILE SYSTEM:
COPING WITH FRAGILITY
● Use Dependency Injection
● Use abstractions
○ e.g. java.nio.file.Path
instead of
java.util.File

32. @nicolas_frankel
DATABASES: COPING WITH FRAGILITY
● Test the Service layer
○ Mock the repository
● Test the Repository layer
○ Mock the database???

33. @nicolas_frankel
DATABASES: COPING WITH FRAGILITY
● Use Fakes under your
control

34. @nicolas_frankel
ORACLE DATABASE USE-CASE
● Use an in-memory data source
and hope for the best
● Use Oracle Express and hope for
the best
● Use a dedicated remote schema
for each developer
○ And your DBAs will hate you

35. @nicolas_frankel
TRADE-OFF
● The closer to the “real”
infrastructure,
the more complex the
setup

36. @nicolas_frankel
MANAGING THE GAP RISK
● In-memory databases are
easy to setup
● h2 is such a database
○ Compatibility modes for
most widespread DB
○ jdbc:h2:mem:test;
MODE=Oracle

37. @nicolas_frankel
WEB SERVICES: COPING WITH FRAGILITY
● Web Services as infrastructure
resources
○ Hosted on-site
○ Or outside
● Different architectures
○ REST(ful)
○ SOAP

38. @nicolas_frankel
WEB SERVICES: COPING WITH FRAGILITY
● Use Fakes under your
control

39. @nicolas_frankel
FAKE RESTFUL WEB SERVICES
● Spark
○ Micro web framework
○ A la Sinatra
○ Very few lines of code
○ Just serve static JSON
files

40. @nicolas_frankel
SPARK SAMPLE
import static spark.Spark.*;
import spark.*;
public class SparkSample{
public static void main(String[] args) {
setPort(5678);
get("/hello", (request, response) -> {
return "Hello World!";
});
get("/users/:name", (request, response) -> {
return "User: " + request.params(":name");
});
get("/private", (request, response) -> {
response.status(401);
return "Go Away!!!";
});
}
}

41. @nicolas_frankel
FAKE SOAP WEB SERVICES
● Possible with Spark
○ But not efficient
○ Remember about ROI!

42. @nicolas_frankel
SMARTBEAR SOAPUI

43. @nicolas_frankel
SMARTBEAR SOAPUI
● Has a GUI
● Good documentation
● Understands
○ Authentication
○ Headers
○ etc.

44. @nicolas_frankel
SOAPUI USAGE
● Get WSDL
○ Either online
○ Or from a file
● Create MockService
○ Craft the adequate response
● Run the service
● Point the dependency to
localhost

45. @nicolas_frankel
CHALLENGES TO THE PREVIOUS SCENARIO
● Craft the adequate response?
○ More likely get one from the
real WS
○ And tweak it
● Running in an automated way
○ Save the project
○ Get the SOAPUI jar
○ Read the project and launch

46. @nicolas_frankel
SOAPUI API
WsdlProject project = new WsdlProject();
String wsdlFile = "file:src/test/resources/ip2geo.wsdl";
WsdlInterface wsdlInterface =
importWsdl(project, wsdlFile, true)[0];
WsdlMockService fakeService =
project.addNewMockService("fakeService");
WsdlOperation wsdlOp =
wsdlInterface.getOperationByName("ResolveIP");
MockOperation fakeOp =
fakeService.addNewMockOperation(wsdlOp);
MockResponse fakeResponse =
fakeOp.addNewMockResponse("fakeResponse");
fakeResponse.setResponseContent(
"<soapenv:Envelope ...</soapenv:Envelope>");
runner = fakeService.start();

47. @nicolas_frankel
FAKING WEB SERVICE IN REAL-LIFE
● Use the same rules as for UT
○ Keep validation simple
○ Test one thing
● Keep setup simple
○ Don’t put complex logic
○ OK to duplicate setup in each
test
■ Up to a point
Author:I,rolfB

48. @nicolas_frankel
IN-CONTAINER
TESTING
INTEGRATION TESTING FROM THE TRENCHES - REBOOTED

49. @nicolas_frankel
INTEGRATION TESTING
● Collaboration between
classes
● Boundaries with external
dependencies
● What did we forget?

50. @nicolas_frankel
DEPENDENCIES
● The most important
dependency is the
container!
○ Spring
○ Java EE
■ Application server

51. @nicolas_frankel
SPRING CONFIGURATION TESTING
● So far, we can test:
○ Beans whose dependencies
can be mocked
○ Beans that depend on fake
resources
● What about the configuration?

52. @nicolas_frankel
DESIGNING TESTABLE CONFIGURATION
● Configuration cannot be
monolithic
○ Break down into fragments
○ Each fragment contains a set
of either
■ Real beans
■ Fake beans

53. @nicolas_frankel
EXAMPLE: DATASOURCE CONFIGURATION
● Production
JNDI fragment
● Test in-
memory
fragment

54. @nicolas_frankel
EXAMPLE: DATASOURCE CONFIGURATION
@Bean
public DataSource ds() {
JndiDataSourceLookup lookup = new JndiDataSourceLookup();
lookup.setResourceRef(true);
return lookup.getDataSource("jdbc/MyDS");
}
@Bean
public DataSource ds() {
org.apache.tomcat.jdbc.pool.DataSource ds
= new org.apache.tomcat.jdbc.pool.DataSource();
ds.setDriverClassName("org.h2.Driver");
ds.setUrl("jdbc:h2:~/test");
ds.setUsername("sa");
ds.setMaxActive(1);
return ds;
}

55. @nicolas_frankel
FRAGMENT STRUCTURE
● Main fragment
○ Repository
○ Service
○ etc.
● Prod DB fragment
● Test DB fragment

56. @nicolas_frankel
TIPS
● Prevent coupling
○ Use top-level assembly instead
of fragment references
● Pool exhaustion check
○ Set the maximum number of
connections in the pool to 1
● Compile-time safety
○ Use JavaConfig

57. @nicolas_frankel
NOW, HOW TO TEST?
● Spring Test
○ Integration with
widespread testing
frameworks

58. @nicolas_frankel
SAMPLE TESTNG TEST WITH SPRING
@ContextConfiguration(
classes = { MainConfig.class, TestDataSourceConfig.class }
)
@RunWith(SpringJUnit4ClassRunner.class)
public class OrderIT {
@Autowired
private OrderService orderService;
@Test
public void should_do_this_and_that() {
orderService.order();
Assert.assertThat(...)
}
}

59. @nicolas_frankel
TESTING WITH THE DATABASE
● Transactions
○ Bound to business
feature
○ Implemented on Service
layer
○ @Transactional

60. @nicolas_frankel
TRANSACTION MANAGEMENT TIP
● When tests fail
○ How to audit state?
○ Spring rollbacks
transactions
● @Commit

61. @nicolas_frankel
TRANSACTION MANAGEMENT
SAMPLE
@ContextConfiguration
@Transactional
@Commit
@RunWith(SpringJUnit4ClassRunner.class)
public class OverrideDefaultRollbackSpringTest{
@Test
@Rollback
public void transaction_will_be_rollbacked() {
...
}
@Test
public void transaction_will_be_committed() {
...
}
}

62. @nicolas_frankel
END-TO-END TESTING?
● Testing from the UI layer is
fragile
○ UI changes a lot
● URL not so much

63. @nicolas_frankel
MOCKMVC
● “Main entry point for
server-side Spring MVC test
support”

64. @nicolas_frankel
MOCKMVC SAMPLE
mockMvc.perform(get("/"))
.andExpect(status().isOk())
.andExpect(view().name("welcome"));

65. @nicolas_frankel
SPRING BOOT

66. @nicolas_frankel
SPRING BOOT
● @AutoConfigureMock
Mvc
● Inject MockMvc

67. @nicolas_frankel
SPRING BOOT
● @SpringBootTest
instead of
@ApplicationContext

68. @nicolas_frankel
SPRING BOOT LAYERED TESTS
● JPA
○ @DataJpaTest
● Web
○ @WebMvcTest
○ @MockBean

69. @nicolas_frankel
THE JAVA EE WORLD
● Java EE has unique
challenges
○ CDI has no explicit
wiring
○ Different application
servers

70. @nicolas_frankel
DEPLOY ONLY WHAT YOU WANT
● Standalone API to deploy only
resources relevant to the test
○ Just pick and choose
● Maven Integration
○ Gradle too…

71. @nicolas_frankel
SHRINKWRAP SAMPLE
String srcMainWebapp = "src/main/webapp/";
ShrinkWrap.create(WebArchive.class, "myWar.war")
.addClass(MyService.class)
.addPackage(MyModel.class.getPackage())
.addAsWebInfResource("persistence.xml",
"classes/META-INF/persistence.xml")
.addAsWebInfResource(
new File(srcMainWebapp, "WEB-INF/page/my.jsp"),
"page/my.jsp")
.addAsWebResource(
new File(srcMainWebapp, "script/my.js"),
"script/my.js")
.setWebXML("web.xml");

72. @nicolas_frankel
MAVEN INTEGRATION SAMPLE
File[] libs = Maven.resolver()
.loadPomFromFile("pom.xml")
.importDependencies(COMPILE, RUNTIME)
.resolve()
.withTransitivity().asFile();
ShrinkWrap.create(WebArchive.class,
"myWar.war")
.addAsLibraries(libs);

73. @nicolas_frankel
DIFFERENT APPLICATION SERVERS
● Abstraction layer to
○ Download
○ Deploy applications
○ Test
● Container adapters
○ TomEE
○ JBoss
○ Weld
○ etc.
● Full Maven integration

74. @nicolas_frankel
ARQUILLIAN TEST SAMPLE
public class ArquillianSampleIT extends Arquillian {
@Inject
private MyService myService;
@Deployment
public static JavaArchive createDeployment() {
return ...;
}
@Test
public void should_handle_service() {
Object value = myService.handle();
Assert.assertThat(...);
}
}

75. @nicolas_frankel
ARQUILLIAN CONFIGURATION SAMPLE
<arquillian xmlns="http://jboss.org/schema/arquillian"
xmlns:xsi="..."
xsi:schemaLocation="
http://jboss.org/schema/arquillian
http://jboss.org/schema/arquillian/arquillian_1_0.xsd">
<container qualifier="tomee" default="true">
<configuration>
<property name="httpPort">-1</property>
<property name="stopPort">-1</property>
</configuration>
</arquillian>

76. @nicolas_frankel
ARQUILLIAN EXTENSIONS
● Persistence: DBUnit
● Graphene: Selenium
● Cube: Docker
● Etc.

77. @nicolas_frankel
Q&A
http://blog.frankel.ch/
@nicolas_frankel
https://bit.ly/2yJvd1Z