Moodle VPL Tutorials

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--D. Thiebaut (talk) 11:51, 19 September 2014 (EDT)

The tutorials below are intended for instructors teaching programming languages, and interested in setting up Moodle VPL modules to automatically test student programs.
The modules are listed in chronological order, most recent at the end. Because VPL is a complex system to master, the early tutorials may not be built using the best approach, but provide functionality. The later modules use more sophisticated features of VPL.
Feel freel to send me your own modules or discoveries, at, and I will be happy to include them here.

Reference Material

(Supporting Files for Video )

  • YouTube video 1: setting up a simple VPL module Part 1 (for use at CCSCNE2015)
  • YouTube video 2: setting up a simple VPL module, Part 2 (for use at CCSCNE2015)

Setting up a VPL module for Python

Moodle Virtual-Programming-Lab (VPL)

Tutorial Language Description

Moodle/VPL Server Setup


This tutorial provides rough directions for setting up two virtual servers that will host Moodle on one of them, and the VPL jail server on the other. This setup is used by the tutorials below on the use of VPL to test student programs.

Moodle VPL Example 1: Hello World!


This tutorial illustrates how to setup VPL to test a simple Python 3 program that prints the string "Hello World!" to the console.

Moodle VPL Example 2: Min of 3 Numbers


This tutorial illustrates how to setup VPL to test a simple Python 3 program that receives 3 numbers from the console and prints the smallest of the 3. The program is tested 3 times, with 3 different sets of input numbers.

Moodle VPL Example 3: Rock-Paper-Scissors


This tutorial shows the settings for a VPL activity that would test a Python program that plays the game of Rock-Paper-Scissors. The program tested is expected to get its input as pairs of letters (PP, RS, PS, etc), indicates the winner of each round, and stops when one player is 3 points above the other.

Moodle VPL Example 4: Gremlins in my File!


This tutorial illustrates how to setup a VPL activity that tests a student program that reads a text file, modifies it, and stores the new content back in the original file. This requires an additional python program that sets up the environment for the first one to run, provides it the information it needs, and captures its output.

Moodle VPL Example 5: Print a 2D chessboard


This tutorial illustrates how to setup a VPL activity that tests a student program that asks the user for an integer and then prints a 2D chessboard (alternating black & white cells) with that dimension. The size of a cell is a 3x3 character on the screen.

Moodle VPL Example 6: Display a rectangle of stars


This tutorial illustrates the setup of a VPL activity to test an assembly language program that displays a fixed string (rectangle of stars).

Moodle VPL Example 7: Assign a grade inversely proportional to the size of the executable


This tutorial illustrates how to setup a VPL activity that will test the size of the executable version of an assembly language program. This can easily be adapted to other languages.

Moodle VPL Example 8: A Hello World Program in Java


This tutorial illustrates how to setup a VPL activity to test a simple Hello World program in Java.

Moodle VPL Example 9: A Multi-File Java Program with A Data File


This tutorial illustrates the setting of a VPL activity that evaluates a 2-class Java project that gets its input from a data file. The project is tested with 4 different data files; one provided by the students, 3 provided by the instructor.

Moodle VPL Example 10: Evaluation Using A Custom Python Program


This tutorial illustrates how to evaluate student work using a custom Python program. Such evaluation allows for more complex testing than enabled by the VPL .cases file.

Moodle VPL Example 11: Testing a Java Class Using another Class as Tester.


This tutorial sets up an environment to test different methods of a Java class provided by the students, and uses a derived class provided by the instructor to activate the student classes.

Moodle VPL Example 12: Using a Java Tester for testing Student Java Program.


This tutorial shows how to setup a more sophisticated testing environment for evaluating and grading Java program.

Moodle VPL Example 13: Testing 2 classes, one Holding a Data Structure, the Other Holding a Test Class.


This VPL module tests two Java classes, one inherited from the other. The test checks that one class does not access directly a member array of the super class (look for presence of [ ] brackets in code). Different grades are given depending on various stages of success.

Moodle VPL Example 14: Testing Student List Class and Verifying Functionality.


This VPL module tests a data structure provided by the student using a class provided by the instructor. The instructor class tests various methods. The grade is proportional to the number of correct output lines.

Moodle VPL Example 15: Looping through Tests in Testing Exceptions.


This VPL module tests how a program uses exceptions to parse a simple text file containing numbers. The script generates 3 tests, and runs through all 3 of them. skips non digits and non minus characters when comparing the output of the submitted program to the expected output.

Moodle VPL Example 16: Catching Programs Stuck in Infinite Loops.


This VPL module is an extension of the previous module (#15), and catches java programs that hang in infinite loops.

Moodle VPL Example 17: Verifying that ASM Program Contains Key Functions.


This VPL module tests that an assembly program actually declares and calls 3 key functions.

Moodle VPL Example 18: Test Function of Student Program Multiple Times.


This VPL module tests a function in the student program and calls it several times to see if it performs correctly. The _start label of the student program is invalidated, and the student program is linked with a test program that calls the student function as an extern.

Moodle VPL Example 19: Feed Different Tests on Command Line.


This VPL module tests a Java program that outputs 0, 1, or several numbers depending on an input provided on the program's command line.

Moodle VPL Example 20: Test Elapsed Time of Student Program


This VPL module tests a Java program and verify that its execution is greater than some predefined amount of time. Otherwise the program may be short-circuiting the execution and outputting a preprocessed answer.

Moodle VPL Example 21: A Java Test Program that Evaluates Student's Submitted Class and Methods


This VPL module uses a Java test program that energizes the student's submitted class, activating various methods, and generates OK or FAIL strings for each test given. The script simply counts the # of OK strings generated and gives grade proportional to it.

Moodle VPL Example 22: Test functions in the student programs, checks stack and register invariance, and verifies that solution provided is recursive.


This VPL module requires the student to submit a program that contains only global assembly language functions. The module uses a test program in assembly that calls the functions with a given set of parameters, and tests whether the returned values are correct or not. The test program also verifies that none of the Pentium registers are modified. The testing script also ensures that the student program uses recursion for his/her solution.

Moodle VPL Example 23: Test a Python program that performs basic input/output operations.


This VPL module is written mostly in Python. vpl_evaluates simply calls a python program that tests the student's python code. The python test first attempts to run the student program as a subprocess to catch possible errors or crash. If this is successful, then the student code is imported and run, with its stdin and stdout redirected from and to files controlled by the test program.

Testing a Bash script


This setup tests a bash script submitted by students. The script acts as a teller machine, getting an integer on the command line and printing 4 integers out, corresponding to the number of $20-bills, number of $10-bills, number of $5-bills, and number of $1-bills.

Testing an Assembly Program with Time-Out


This setup tests a recursive program in assembly (binary search) that may time-out (possibly because of weird recursive coding.) The evaluate script will abort if the program takes longer than a specified amount of time. This uses a bash script for and

Testing a C Program


This setup tests a C program that is supposed to replicate some of the functionality of the Linux grep command. In particular, the C program should get its input from the command line and support the "-i" switch, for case-insensitive searching.

Tips & Tricks


A collection of notes, recommendations, tips, tricks, and modifications. For example, we describe how to strip comments from java or assembly language comments.