JGrade2
My Experiments | | Links: Github Repo
An updated plugin for Gradescope users to grade Java submissions like a pro. Updated now for Java 21 and JUnit5 with easy Maven integration.
I (kinda) don’t like Java
As a daily driver, I am not a fan of the Java language. Its verbose and clunky syntax is reminiscent of the old days when programming was more about creating the code space than playing in it. As someone who starts a new project every other week, Java’s framework setup eats into those precious few days. However, I do think Java has its place. Its accessibility and standardization make it a well-suited choice for large, legacy-focused systems. Its verbosity is a feature, not a bug- in some cases- and is excellent for “fine-grained control” over a system. Thus, while I discourage programmers from using Java, I heavily encourage computer science students to master it.
All that is to say, when a professor and colleague came to me for help on this project, I was more than happy to oblige. Not only was it a chance to eliminate more tediousness in this world, but I will never say no to scoring some brownie points with a colleague.
Outdated-ness
This project is less about the intricacies in Java auto-graders and more about awareness to not only this tool but also the need for versioning, dependency checks, and long-term support. Here’s the issue: A legacy-coding class utilizes JUnit for auto-grading assignments. From unit tests to end-to-end integration checks, this class and the university partner with Gradescope to manage student submissions. (There is also test coverage and mutation testing in the works, but that is a different story.) Origionally written in 2019, @tkutcher wrote the first JGrade to compile Junit’s (v4) output to Gradescope specification. However, as time moved on from the pandemic, so did Junit, and it upgraded to version 5, completely breaking JGrade. While not really a problem if the class locked the version of Junit to v4, they were also updating to Java 21, which was not compatible with Junit4. Stuck between a rock and a hard place, the class implemented a workaround for the time being (i.e., the computing power of the TAs).
Enter jGrade2
I will be frank: this project was more a 2-week exercise of entering and updating a legacy codebase, ironically mirroring the concepts taught in the class this was originally for. Immersing myself into the codebase was easy thanks to @tkutcher’s excellent demonstration of code organization (thank you, Tim!). A glance at the changelog from Junit4 to 5 brought me about 90% of the way there with understanding which methods to update. The other 10% was a matter of understanding the stack trace and creating some test cases to verify sanity. All in all, the main issue came from a rewrite of how Junit5 exposed its test discovery, progress, and results. Since this post won’t be complete without some code, here is a snippet of the rewrite:
// file: `src/main/java/com/github/jgrade2/jgrade2/Grader.java`
public void runJUnitGradedTests(Class<test> testSuite) {
LauncherDiscoveryRequest request = LauncherDiscoveryRequestBuilder.request()
.selectors(selectClass(testSuite))
.build();
GradedTestListener listener = new GradedTestListener();
LauncherSession session = LauncherFactory.openSession();
Launcher launcher = session.getLauncher();
launcher.registerTestExecutionListeners(listener);
TestPlan testPlan = launcher.discover(request);
launcher.execute(testPlan);
...
Conclusion
And that was pretty much it! The rest of the time was spent creating a new Github organization to host the update in, giving proper credit to @tkutcher, rewriting the examples, establishing a CD/CI pipeline, and registering it onto Maven Central for easy use! Please feel free to check it out and implement it in your classroom workflow. It’s usage is the same as the origional JGrade, with a new dependency import if you use Maven. If you’re too lazy to check out the repo, you can add it to your project with the following addition to your pom.xml:
<dependency>
<groupId>io.github.jgrade2</groupId>
<artifactId>jgrade2</artifactId>
<version>${jGrade2.version}</version>
</dependency>
Thanks for reading this short project! I hope you’re able to get some use out of this new plugin!
