WeBWorK Java Evaluator

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WeBWorK Java Evaluator

• Nathan Baur

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Summary

• Project Goals
• What is a Course Management System?
• How does the Java evaluator work?
• Framework
• JUnit testing
• Writing problems

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Project Goals

• Gently introduce programming concepts
• Grade code fragments or entire programs
• Provide specific feedback to help students
  identify the problems with their code
• Provide professors with an easy, flexible system
  for writing questions
• Integrate the evaluator into an existing Course
  Management System

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What it looks like
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What is a Course Management System?

• Tracks grades and assignments automatically
• Some grade certain types assignments
  automatically, providing immediate feedback
• Popular CMSs include Moodle, Blackboard and
  WeBWorK

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Why choose WeBWorK?

• Open-source
• Flexible, modular design
• Well supported
• Already used by a number of institutions

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How does the evaluator work?

• Students are provided with a simple WeBWorK
  interface to input code

Student
WeBWorK
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How does the evaluator work?

• Student code is sent from WeBWorK to the Java
  Evaluator module, which inserts the code into a
  template file to create a complete Java class

Student
WeBWorK
Evaluator
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How does the evaluator work?

• The Java evaluator launches problem-specific
  JUnit tests to be run on the student code

Student
WeBWorK
Evaluator
JUnit
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How does the evaluator work?

• JUnit returns the results to the Java evaluator
  module

Student
WeBWorK
Evaluator
JUnit
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How does the evaluator work?

• The Java evaluator formats the results into a
  message for feedback which is sent to WeBWorK

Student
WeBWorK
Evaluator
JUnit
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How does the evaluator work?

• WeBWorK gives the students feedback and gives
  them the opportunity to fix the code and try
  again.

Student
WeBWorK
Evaluator
JUnit
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JUnit

• Unit testing framework
• Tests are written in Java using JUnit classes
• Code can be tested for any circumstance
• Custom failure messages can be provided based on
  how the test failed

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Writing problems

• WeBWorK PG file in perl
• Includes the problem description and specifies
  the .java files to be used by JUnit
• Template .java file
• Usually minimal
• Includes class definition and problem-specific
  setup so that students dont have to deal with it
• JUnit test file
• Includes the tests and feedback messages

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Sample PG file

• DOCUMENT() This should be the first
  executable line in the problem.
• loadMacros(
• "PG.pl",
• "PGbasicmacros.pl",
• "PGchoicemacros.pl",
• "PGanswermacros.pl",
• "PGauxiliaryFunctions.pl",
• "javaAnswerEvaluators.pl"
• )
• BEGIN_TEXT
• Hello World! PAR Given a String object myString,
  assign it to "Hello World! BR
• \ANS_BOX(1,1,30)\
• END_TEXT
• ANS(java_cmp("JavaSampleSet/HelloWorld/","HelloWor
  ld"))
• ENDDOCUMENT() This should be the last
  executable line in the problem.

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Sample .java template file

• public class HelloWorld
• private String myString
• public HelloWorld()
• doIt()
• public void doIt()
• replaceme
• public String getMyString()
• return myString

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Sample JUnit test file

• import junit.framework.
• public class HelloWorldJUnitTest extends
  TestCase
• private HelloWorld hw
• private String ans "Hello World!"
• public void testDefined()
• Assert.assertTrue("Assigning the
  variable", hw.getMyString()!null)
• public void testCorrect()
• Assert.assertTrue("Making it say exactly
  \"Hello World!\" , hw.getMyString.equa
  ls(ans))
• public static Test suite()
• return new TestSuite(HelloWorldJUnitTest.c
  lass)

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Acknowledgements

• Andy Wildenberg
• Jacqueline Baldwin
• Christelle Scharff
• Cornell College
• PACE University
• Made possible by NSF grant 0511391