For a long time now, the Eclipse Rich Client Platform has suffered from a severe lack of support for one of the core elements of Agile programming--Continuous Integration. The support for building and packaging an RCP application through the IDE itself was very different from the headless support for those same tasks through PDE/Build. The testing support for JUnit 4 available through the IDE was not even present in the Eclipse Test Framework. The situation has markedly improved in Eclipse 3.6 with advances in the Eclipse Test Framework and the addition of Buckminster and p2 as a possible replacement for PDE/Build, but setting up a continuous integration system for Eclipse RCP remains a time-consuming and difficult task. An Agile project really needs to have continuous integration up and running hopefully from day one. To make this easier, I've created a quick-start template project called Lightning, which demonstrates how to effectively combine Buckminster, the Eclipse Test Framework, and SWTBot for integration tests. It has been tested on Linux and Windows, though Buckminster on the Mac seems to still have a few kinks to work out.
Buckminster touts itself as a system that works the same headlessly as it does in the IDE, and while not fully living up to that promise yet, it comes close. Nevertheless, for our build we chose to simply kick off the headless version of Buckminster through ant--a solution that works equally well anywhere. In fact, since the headless version of Buckminster is a little hard to get installed, we put that into the build process as well. This uses the p2 director application available from the Buckminster download site.
The first step is to download Lightning and unzip it. Because we are using Buckminster, we can actually materialize our target platform for the project from the Helios p2 repository. To do so, simply navigate to the buckminster.build.feature and run the command "ant materialize.target.platform", which will materialize the target platform to a directory <unzip location>/lightning/workspace-target-platform. That will serve as the target platform for the IDE workspace, and includes plugins the actual build doesn't need, such as source for Eclipse. Import the lightning plugins into a new Eclipse 3.6 workspace, switch the target platform to the new platform you just materialized, and you should be all set to follow the code for the rest of this blog.
We'll start with a quick rundown of the tools we use for building and testing our new RCP product.
At the top level ant is used to manage all the other tools. It provides the top-level targets, and gives us everything we need to actually run the build from Eclipse, the command line, or Hudson. For more information on ant, see the Ant Manual.
p2 is the provisioning system in Eclipse, replacing the old update manager. It is available both within the IDE as well as in a stand-alone utility Eclipse distribution that is intended to be run from the command line. p2 can be used to both download and install Eclipse plugins and RCP products. For more information on p2, see the p2 Wiki.
Buckminster is a build system for Eclipse products and plugins, and can be run from within the IDE (with the proper tooling installed) as well as headlessly from the command line. We use the command-line version in our build system, so no additional tooling is required in the IDE. Buckminster can inspect artifacts such as plugins and features in order to determine all of their dependencies, and can pull those dependencies from p2 repositories. Buckminster is somewhat similar to Maven, but with a focus on Eclipse artifacts. For more information on Buckminster, try to read through the Buckminster Manual. No really. Go on. I dare you.
Eclipse Test Framework
The Eclipse Test Framework allows us to run JUnit4 tests as plugin tests from the command line. This means that the tests run within the OSGi environment provided by Eclipse, and have access to things such as the Extension Registry.
SWTBot is a framework for running tests that interact with the user interface directly. These can be used to click buttons and check results from the user interface, and we use this for User Acceptance Testing. SWTBot comes both as a set of tools for use in the Eclipse IDE as well as in a headless distribution. We use the headless distribution in the build process, but include the other tools in the workspace target platform. They do not play very well together.
We really haven't created a continuous integration system until we're actually running it continuously. Hudson is my favorite CI system, and is quite easy to set up. Hudson includes a Buckminster plugin, but we since we can launch everything through ant, we don't actually need it. By relying on ant we ensure that the build can be run both from the developer box as well as the continuous integration system without risking differences in configuration.
Now that the tools are out of the way, let's take a look at the build process itself. You can kick off the full build process by just running the command "ant" from the buckminster.build.feature directory.
The first step in the build process installs the p2 utility, called the "director". This in turn is used to install the headless version of Buckminster. The next step uses Buckminster to build the product.
There are two products we will build in this process. The first is the test product, which will include everything in the production product along with all tests and test dependencies. The second product is the actual production product that we can then ship to our customers. If it seems a little strange that we need two products, just remember that we're actually going to run our tests inside an OSGi environment, and so we need everything packed into plugins, including our test code.
When Buckminster runs, it needs to run in an Eclipse workspace, in just the same way it would run if we were running it from within the IDE. The first step of the Buckminster script we run sets up a new workspace and target platform in order to allow Buckminster to build. The target platform is imported using a target definition file, which simply tells Buckminster where to place any plugins it later downloads for the target platform. Next, the import command actually executes an import of those plugins as defined in a "cquery" file. The .cquery file points to an Eclipse feature that was created especially for Buckminster, along with a list of places to find all the plugins that are included in that feature, which is stored in an "rmap" file.
The rmap points to a few different places to find plugins. Some of these are from p2 repositories on the internet, some are from our local source project checkouts, and some are from local p2 repositories. The local p2 repositories were actually created earlier in the build process using the p2 director application and a list of pre-built plugins. Once the cquery is imported, Buckminster has a fully materialized target platform along with all of the checked out projects imported into its own workspace area, and is now ready to build the projects. Note that we could have set up our build to use the workspace-target-platform we've already created and the build would probably be a bit faster, but we wanted to show how Buckminster can pick out all of the plugins it needs and assemble a target platform on the fly. Notice that we had to create a local p2 repository for the Eclipse Test Framework as well. In the future we hope that Eclipse will put the ETF into one of their public p2 repositories, and in fact there is a bug out there for that right now.
Once we build all the plugins in the workspace with Buckminster, we execute a Buckminster target. The normal target we would execute would be one that is automatically created for us by Buckminster by virtue of the fact that we are inside an Eclipse feature. That target is called site.p2, and tells Buckminster to install all of the plugins into a new temporary p2 repository. From there we could do whatever we like with them. In our case, however, we have added a different target in a "cspex" file. This target will call site.p2, but also use p2 to install the product into the file system. In this case, we install our test product with the command "create.product.test". Notice that this command actually runs an embedded version of ant that comes with Buckminster to perform the work.
After our test product is installed in the file system, we need to run the tests using the Eclipse Test Framework. The Eclipse Test Framework includes an ant file to run it, but this ant file was a little limited, so we replace that functionality in our own ant file. The test framework is launched as an Eclipse application, and can only run a single test or test suite at a time. Because of that we have created an AllTests suite for each plugin fragment.
The test target in ant launches the test framework from within our test product that we installed earlier. It passes in the plugin that contains the tests for our test fragment, and then saves the resulting JUnit test reports. These test reports can be displayed by Hudson or the Eclipse IDE. It also runs the SWTBot tests in a very similar manner, and saves the results as well.
Assuming all tests pass, we package the final product. The build system can package the product for multiple platforms.
I hope this project is useful to some of you Agile RCP developers out there. Let me know how it works out for you, or if you have any questions.