Thursday, September 29, 2011

No new JUnit release announcements, period, here.

If by chance you've been following this blog in order to get announcements of new JUnit releases, whether beta or final, this is the last time they are likely to be posted here. You can follow along at, or the mailing list. I'll be keeping this blog for whatever comes to mind that is more exciting that JUnit releases, which are becoming more predictable and mundane. By the way, JUnit 4.10 is released. Share and Enjoy!

Thursday, September 22, 2011

No new beta-release announcements here

Hi, all. In order to reduce the noise until there's time to raise the signal here, I'm going to start only announcing JUnit beta releases on the main user's mailing list: If you are a devoted beta-tester, and that's a problem, let me know. Thanks.

Tuesday, August 23, 2011

JUnit 4.9 released

Over a year in the making, we are happy to announce the release of JUnit 4.9.

This release's theme is Test-class and suite level Rules. The release notes are copied in part below, and can be read in full here.

Go ahead and download, or merely let maven do the work for you (as we are now directly releasing to sonatype's maven repository on the same day we release the jars).

Following this release, work on JUnit and related code will continue on three fronts:

  • Bug fixes against existing functionality will be committed to the 4.9.1 branch.
  • New core features will be committed on the 4.10 branch.
  • We have created a new junit.contrib project to be a home to new experimental features, features that use additional dependencies, and features that are outside of JUnit's core mission. As a first example, Thomas Mueller has created assertthrows, a package that uses all kinds of JDK trickery to allow direct assertions like this:
      List<String> emptyList = new ArrayList<String>();
We are excited that github allows extensive community participation and discussion in the ongoing development. Please pitch in! Remember, JUnit celebrates programmers testing their own software. Let's build something.

JUnit 4.9 release notes (highlights)


The ClassRule annotation extends the idea of method-level Rules, adding static fields that can affect the operation of a whole class. Any subclass of ParentRunner, including the standard BlockJUnit4ClassRunner and Suite classes, will support ClassRules.

For example, here is a test suite that connects to a server once before all the test classes run, and disconnects after they are finished:

@SuiteClasses({A.class, B.class, C.class})
public class UsesExternalResource {
    public static Server myServer= new Server();

    public static ExternalResource resource= new ExternalResource() {
        protected void before() throws Throwable {

        protected void after() {


In JUnit 4.9, fields that can be annotated with either @Rule or @ClassRule should be of type TestRule. The old MethodRule type, which only made sense for method-level rules, will still work, but is deprecated.

Most built-in Rules have been moved to the new type already, in a way that should be transparent to most users. TestWatchman has been deprecated, and replaced by TestWatcher, which has the same functionality, but implements the new type.

Maven support

Maven bundles have, in the past, been uploaded by kind volunteers. Starting with this release, the JUnit team is attempting to perform this task ourselves.

LICENSE checked in

The Common Public License that JUnit is released under is now included in the source repository.

Friday, August 12, 2011

JUnit 4.9b4 (beta-)released

This release's theme is Test-class and suite level Rules. This beta release contains a number of community-authored fixes for regression errors in documentation and test class validation. Please read the release notes, download, and give feedback before the final release.

[Edit: fixed release notes link]

Wednesday, July 6, 2011

JUnit 4.9b3 (beta-)released

Five months and a dozen regression errors later, JUnit 4.9b3 is now ready for your testing pleasure. This release's theme is Test-class and suite level Rules. Please read the release notes, download or slurp from Maven, and give feedback before the final release.

Tuesday, March 22, 2011

New project: junit.contrib

I'm planning to start a junit.contrib project.
In this post, I'll first review the reasons for such a project, and
secondly, I have a proposal for its structure, and I'd like feedback.

Background: reasons for junit.contrib

JUnit has always officially strived to be "the intersection of all
useful Java testing frameworks". Thus, the goals for code that gets
into the junit repository include that it should:

  1. Minimize dependencies on external libraries or particular JDK
    versions beyond a widely-used minimum.
  2. Be very unlikely to change API moving forward.
  3. Emphasize opportunities for extension over the richness of core features.
  4. Have potential usefulness to all Java developers, regardless of
    their application domain.
  5. Match in style to the current JUnit codebase.
Many people have made JUnit extensions that would be useful to a healthy portion of Java developers, but do not meet all of the above criteria. For example, the extension may target a particular IDE, or data that is stored in a SQL database, or in XML, or it may be experimental, and likely to change API, or it may require an external dependency. Also, as the popularity of non-Java languages on the JVM has grown, some people have made extensions to JUnit that make it easier to use JUnit's core functionality in ways idiomatic to those other languages. It has always been an option for developers of these extensions to publish them on their own repositories. However, having a central clearing-house as an option for extension developers has some advantages, including discoverability, documentation, and dependency management. The goal is for junit.contrib (just started here) to be this clearing house. All Java classes in this project should be in packages prefixed with org.junit.contrib. Now, the


The root structure of the project will contain:
 scala/ [?]
 clojure/ [?]
Thus, a folder for overall documentation, and then a folder per-language. I haven't thought about how non-java language extensions should be organized. Under java, there should be a folder per "subproject" (names chosen, with apologies, by my favorite naming tool):
Each subproject should be organized as its own maven project:

As potential users and contributors to such a repository, are there
pitfalls in this organization that I should be aware of in advance?

Thursday, January 27, 2011

Very very simple testing in bash

Imagine I'm starting today on a software system that I expect to spend
at least a year on. Being me, somewhere in the top five questions I
ask myself is "How am I going to test this?" Frequent automated testing
gives me confidence that I won't find out next week that today I broke
something that was working last week. Writing tests is also an important way
to organize my thinking about what I'm doing. Once I've spent time specifying
where I'm going, it's easier to get there quickly.

Since I'm going to be spending a year on this, it's worth my time to invest time
in tools and frameworks that will make specifying and running these tests easy.
I might even write some of my own.

However, suppose that I'm working on a quick demo that I'm only going to spend
a couple weeks on. Or a data-processing script that I need to have finished
tomorrow. Or a sysadmin task that I expect will only take half an hour?

In these cases, I still want the benefits of testing, but I want to spend
as little time as possible getting started. Also, it's not always clear
what technologies I'll be using: I may start in Java, and then find that
a Python library will give me 80% of what I need.
So, I've started to write start projects with test suites that consist of
nothing more than a bash script with a standard footer I copy-and-paste
from project to project. The advantages:

  • Fast startup: I don't need to download anything or
    run through any "new project" wizards.
  • If my project lasts longer than I expected, it's easy to remember how
    to run the tests: just run the script.
  • I can easily refactor to use a more heavyweight framework like JUnit by
    calling out to it from the script.
  • It isn't tied to any underlying implementation choice.
  • Perhaps best of all, it rewards a UNIX style of small stdin-to-stdout
    plug-and-play components.

With no further ado, here's an example script, this one drawn from
the JUnit build process:

Friday, January 21, 2011

JUnit 4.9b2 (beta-)released

This release's theme is Test-class and suite level Rules. Please read the release notes, download, and give feedback before the final release.

Tuesday, January 4, 2011

Running a JUnit 4 test from a Scala script

I'm using Scala now and then as a language for side projects. One of the nice things about Scala is that you can bootstrap with a single-file script, similar to Python or Ruby. Since I enjoy building things with test-driven development, it's not long after I write a script that I want to start writing tests for classes and functions. However, when I tried to do this in the straight-forward way, it doesn't quite work. Herein, the problem, and its solution.

As a first attempt, I expected this to work:

However, running this produces a failure in the infrastructure:

What's going on here is that when scala is run in single-file script mode, it implicitly wraps all of the declarations within the declaration of an anonymous singleton object (Main$$anon). When JUnit tries to reflectively create an ArithmeticTest object, it runs into the fact that, from the Java perspective, ArithmeticTest is a non-static inner class of Main$$anon. To get around this requires a bit of a dance, luckily made fairly short due to Scala's compact OO verbiage:

If I find myself doing this often, I imagine I'll be pulling this out into an importable library. Share and Enjoy.