profcab / vpl-unit-test

A short HOWTO on creating a VPL activity that uses unit tests to grade the assignment.

vpl-unit-test

Virtual Programming Lab is a powerful plugin for Moodle that allows students to upload programming assignments for automatic grading. If you are teaching a programming course with hundreds of students, I imagine you don't need too much convincing that this is a good idea :-)

This is a very brief HOWTO on creating a VPL activity that uses unit tests to grade the assignment. Thanks to Juan Carlos for explaining it to me on the VPL Forum. This example uses Java but it should be easy to adapt to other languages, testing frameworks etc.

1. Create a VPL activity in the usual way. There is no need to define tests in vpl_evaluate.cases.
2. Create a suite of unit tests that you want to use to grade the activity, e.g. MyTest.java. Add this file or files to the Execution Files section in your activity.
3. Create a second class which runs the tests in MyTest "manually", as it were -- i.e. by calling the tests individually rather than using the JUnit test runner. See the example in src/Main.java. Again, add this file to the Execution Files for the activity. As well as calling the tests, the Main class has to calculate the grade and emit comments and a grade in the format required by VPL. Anything other than comments and a single grade is ignored and you must use the exact formats used in Main.java. If your test suite contains several tests, each of which should constitute part of the mark, make this calculation yourself in the Main class. Then print out any explanation you want to give to the student in comment sections and a single overall Grade :==> n line at the end of the output.
4. Create a vpl_run.sh script which allows the student to run the test suite. See etc/vpl_run.sh for an example. Edit the script to contain the correct path to the JUnit jar on your jail server if necessary.
5. Create a vpl_evaluate.sh script which allows the student to evaluate their code and receive a mark. See etc/vpl_evaluate.sh for an example. Again, make sure the path to the JUnit jar is correct.