= iTests Overview
:jbake-type: page
:jbake-status: published

== Motivation

The basic idea behind itests that makes them slightly different than plain junit tests ran by maven is that it's assumed that there are other systems (servers, databases, brokers, etc) that need to be started or connected to before the tests can run.
The tests themselves don't setup the other systems themselves so that the tests don't become coupled with them and you can actually swap out various aspects of those systems behind the back of the tests;
server version, protocol implementation, java version, VM implementation, database provider, operating systems, even using embedded servers and embedded databases.

The idea came from the tests in OpenEJB that do this.
It took a lot of work to get them to run as part of the maven build and the itest plugin was the result.

Definitely give those a look at:  http://svn.apache.org/viewvc/tomee/tomee/trunk/itests/

== Plugging in

You can have systems started and stopped before and after the tests in a number of ways.

=== In maven 1

This series of articles established a basic technique for Container Driven Testing with Maven and OpenEJB using preGoals and postGoals to do server and databse setup and teardown before and after Maven runs the unit tests.
http://www.theserverside.com/articles/article.tss?l=ContainerDrivenTestingSeries

This concept evolved from OpenEJB into a reusable maven plugin created by Dain Sundstrom that gave these integration tests (itests) their own source directory and added itest:setup and itest:teardown goals to your maven build rather than just using a preGoal on "test:test" for setup and a postGoal on "test:test" for teardown.
The advantage to the new goals is that maven does not call any postGoals on "test:test" if the tests failed;
something the above series of articles hacked around with an odd bit of jelly code.

The new itest plugin was checked into Geronimo with the expectation that Geronimo would also use it.
After some time of OpenEJB still being the only consumer of it, it was moved into the Maven repository where they keep it in the Maven sandbox.

http://maven.apache.org/plugins-sandbox/itest/

ActiveMQ later started using the itest plugin and now has a large suite of their own JMS specific integration tests.

=== In maven 2

The concept of integration tests (itests) has been built into the lifecycle of maven 2, so it is no longer required to have the itest plugin around to get the extra "itest:setup" and "itest:teardown" goals.
See this document for more info:  http://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html

=== In junit setup and teardown

The ejb tests in particular require you to plug in facades for the server and the database so the client (the tests) can say "give me an initial context" or "create these tables i need" in a generic way.
It's assumed that those systems were setup and guaranteed in working state in the itest setup phase.
It's also guaranteed that the server and database facades know how to contact the server or database to carry out the "give me an initial context" and "create these tables" calls.

Here are some implementations of the database provider for reference:   - http://cvs.openejb.org/viewrep/openejb/openejb/modules/itests/src/itest/org/openejb/test/AxionTestDatabase.java   - http://cvs.openejb.org/viewrep/openejb/openejb/modules/itests/src/itest/org/openejb/test/DerbyTestDatabase.java   - http://cvs.openejb.org/viewrep/openejb/openejb/modules/itests/src/itest/org/openejb/test/InstantDbTestDatabase.java   - http://cvs.openejb.org/viewrep/openejb/openejb/modules/itests/src/itest/org/openejb/test/PostgreSqlTestDatabase.java

Here are some implementations for the server facades:   - http://cvs.openejb.org/viewrep/openejb/openejb/modules/itests/src/itest/org/openejb/test/CorbaTestServer.java   - http://cvs.openejb.org/viewrep/openejb/openejb/modules/itests/src/itest/org/openejb/test/RemoteTestServer.java   - http://cvs.openejb.org/viewrep/openejb/openejb/modules/itests/src/itest/org/openejb/test/IvmTestServer.java   - http://cvs.openejb.org/viewrep/openejb/openejb/modules/itests/src/itest/org/openejb/test/RiTestServer.java

Using the itest concept you could setup any system you need before hand, then just provide an abstraction of that system to the actual tests.
So it's not limited to just a server or a database.
You could do queue, topic, clustering heartbeat agent, directory server, etc.

== Testing matrix

Even with just what we have we can get quite far.
In a perfect world, we would actually test against the full matrix:

Server: Local, Database: Axion   Server: Local, Database: Derby   Server: Local, Database: PostgreSQL   Server: Remote, Database: Axion   Server: Remote, Database: Derby   Server: Remote, Database: PostgreSQL   Server: Corba, Database: Axion   Server: Corba, Database: Derby   Server: Corba, Database: PostgreSQL

We had that going for a short while years ago but it was just too much infrastructure for me to keep running.
It would be nice to get Oracle and MySQL in that list as well.

In an even more perfect world we'd test against not just different Server and Database combinations, but JVM versions as well.

Server: Local, Database: Axion, JVM: 1.3   Server: Local, Database: Axion, JVM: 1.4   Server: Local, Database: Axion, JVM: 1.5   Server: Local, Database: Derby, JVM: 1.3   Server: Local, Database: Derby, JVM: 1.4   Server: Local, Database: Derby, JVM: 1.5   Server: Local, Database: PostgreSQL, JVM: 1.3   Server: Local, Database: PostgreSQL, JVM: 1.4   Server: Local, Database: PostgreSQL, JVM: 1.5   Server: Remote, Database: Axion, JVM: 1.3   Server: Remote, Database: Axion, JVM: 1.4   Server: Remote, Database: Axion, JVM: 1.5   Server: Remote, Database: Derby, JVM: 1.3   Server: Remote, Database: Derby, JVM: 1.4   Server: Remote, Database: Derby, JVM: 1.5   Server: Remote, Database: PostgreSQL, JVM: 1.3   Server: Remote, Database: PostgreSQL, JVM: 1.4   Server: Remote, Database: PostgreSQL, JVM: 1.5   Server: Corba, Database: Axion, JVM: 1.3   Server: Corba, Database: Axion, JVM: 1.4   Server: Corba, Database: Axion, JVM: 1.5   Server: Corba, Database: Derby, JVM: 1.3   Server: Corba, Database: Derby, JVM: 1.4   Server: Corba, Database: Derby, JVM: 1.5   Server: Corba, Database: PostgreSQL, JVM: 1.3   Server: Corba, Database: PostgreSQL, JVM: 1.4   Server: Corba, Database: PostgreSQL, JVM: 1.5

If you add JVM vendors (Sun, IBM, Apple, BEA) to the list, the combinations goes up to like 109.
Throw on OS implementations and you get an insane number of test runs to complete.