Sigcse2009 Workshop: Ex.4: Configuring Coding Style Checks



In this exercise, we will explore some additional grading options you can use to tailor the processing of your assignments. You will also create a second assignment of your own.

Learning Objectives

  • Mastery of configuring a grading plug-in
  • Familiarity with plug-in reusable option sets
  • Familiarity with the basic options for the JavaTddPlugin
  • Exposure to providing data files for student testing
  • Exposure to configuring PMD checks
  • Exposure to configuring Checkstyle checks
  • Exposure to configuring score settings for static checks

A New Example

For this exercise, we will use a new example taken from Virginia Tech’s CS 1 course. This example is a web log analyzer that reads Apache-style web server logs. It tabulates hit rates by day of the week and hour of the day. We’ll load it into a new Eclipse project, set up a new Web-CAT assignment for it, and then tweak the assignment’s settings.

Create a New Project in Eclipse

Now that you’ve worked with the Calculator example for a while, let’s switch gears and work with a new example.

In Eclipse, select the File->New->Project… menu and select Java Project. Name it Log Analyzer and accept defaults for the other settings.

Add these two files to your new project: and They won’t compile yet, however.

Also, download cs1705.jar and place it into your new Eclipse project as well (you can drag it into your project in the Package Explorer view).

Right-click the cs1705.jar file in the Package Explorer and select Build Path->Add to Build Path.

Finally, right-click on your LogAnalyzer project in the Package Explorer view and select Build Path->Add Libraries…, select JUnit from the resulting list, and click Finish. This should clear up any remaining compiler errors in the project.

However, if you run your tests, all the tests will fail! That is because the VTLogAnalyzerTest class uses an external log file as the input for its tests, and your project does not contain this file yet.

Download sample.log and add it to your LogAnalyzer project and re-run your tests.

Create a New Web-CAT Assignment

In your web browser, click the Assignments tab and create a brand new assignment for the web log analyzer. Use your initials to provide the name (e.g., “SE 2” or “MPQ 2”). Choose the same submission rules as you used for your first assignment (should be named with your name).

Add the JavaTddPlugin to the grading scheme. Click the edit icon for the JavaTddPlugin entry, and select your reusable option set (again, look for your name). Do not worry about reference tests for this assignment. We’ll go without them this time. You can come back and add them after completing this exercise, if there is time.

After selecting your reusable option set, click “Next” to go back to your assignment’s properties. Make sure to check “Publish It”, and then Finish.

Make a Test Submission

From Eclipse, make a test submission from your LogAnalyzer project. Make sure everything looks OK.

All of your tests should have failed! While you’ve added the sample.log file to your project, it was not included in your submission to Web-CAT. Web-CAT assignments are configured by default to exclude any *.log, *.dat, *.bin, *.zip, *.jar, etc. files from submissions. After all, we don’t want many, many copies of the same files constantly going back and forth to the server, for each and every student. In fact, Web-CAT imposes a cap on the size of project submitted by students (controled by the submission policy for your assignment), with a default of 200K.

Add a Data File to Your Assignment

To resolve this situation, let’s configure the assignment to provide a stock set of data files when running each student’s tests. The same set of files will be available for everyone, without students having to submit their own independent (but identical) copies.

In your web browser, click the Assignments tab and navigate to your web log analyzer assignment’s properties.

Click on the edit icon for the JavaTddPlugin step in the grading scheme.

Under the Assignment-Specific Options section in the lower half of the window, look for the Data Files for Student parameter and click its Browse button.

Upload your sample.log file, and then select it as the data file to provide. For other assignments, you could upload an entire directory of data files (or a zip archive that you could expand on upload to populate an entire directory tree). If you select a directory, the contents of that directory are made available in the current working directory during grading. If you select a single file, then that single file is provided in the current working directory during grading. These files can be used in either student-written tests, instructor-written reference tests, or both.

Click Finish to save your work.

Regrade Your Submission

Rather than resubmitting your project, let’s use Web-CAT’s regrade feature. Click the Grading tab and navigate to your new web log analyzer assignment.

Click the edit link in the TA column for your submission to view your submission results.

Look for the Regrade Submission button near the top of the page. Click it, and then click OK to regrade this submission.

Use the Results tab to look up your new results. Did all your tests pass?

Note that when Web-CAT regrades an assignment, it puts it at the back of the processing queue. Fresh assignments always take precedence over regrading actions. However, once the regrading is completed, Web-CAT will notify the student by e-mail.

Relevant Cookbook Recipes

Regrade One Student
Regrade All Students

Examine Static Analysis Scoring

While all your tests should now pass, you will still receive less than a perfect score. That is because the solution you are using does not follow all of the coding conventions enforced by Web-CAT’s static analysis tools. The sample solution, adapted from a sample project in Barnes and Kölling’s Objects First with Java book, does not follow the same conventions.

Under the Results tab, look inside the files you submitted and view the detailed comments provided for an example.

The JavaTddPlugin automatically deducts points for static analysis violations. It uses a Java-style properties file to define the penalties for each offense. You can see the JavaTddPlugin’s default scoring scheme here:

In the future, you can edit and then upload your own custom version of this penalty file using your assignment’s reusable option set.

Configure PMD Checks

Rather than directly editing the static analysis scoring file, however, let’s simply disable the static checks. The process used here is the same one you would use if you were planning to add, remove, or customize the checks performed. We’ll start with PMD.

PMD is an open-source static analysis tool for Java. It provides a large collection of static analysis checks, many of which embody accepted best practices for coding style.

PMD is controlled by an XML file that defines the configuration you wish to use when checking student code. To change the behavior of PMD, simply provide a new configuration file for it.

For now, let’s just turn off the PMD checks. We can do this with an XML configuration file that tells PMD to shut off all checks: pmd-None.xml.

In Web-CAT, click the Assignments tab and navigate to your web log analyzer assignment.

Click the edit icon for the JavaTddPlugin.

Click the edit icon for your reusable option set.

Choose Static Analysis from the “Show:” drop-down list.

Click the Browse button for the PMD Configuration parameter.

Upload and then select the pmd-None.xml file.

Click Finish to save your changes.

For reference, the checks provided by the JavaTddPlugin’s default configuration are defined in pmd.xml, which indirectly refers to several other files. You can write your own XML file that refers to some or all of these customized rules, or that suppresses specific rules. Check out the PMD project’s instructions on how to make a rule set.

Configure Checkstyle Checks

Checkstyle is another open-source static analysis tool for Java. Many of its checks overlap those in PMD, but it also provides some unique checks of its own.

Like PMD, Checkstyle is also controlled by an XML configuration file that defines which checks are enabled. Customizing the set of Checkstyle rules that are enabled works just like it does for PMD. Just upload your custom Checkstyle XML configuration file.

To turn off all Checkstyle checks, for example, edit your assignment’s properties, and go into the JavaTddPlugin’s reusable option set again. Under the Static Anaylsis category, look for the Checkstyle Configuration parameter.

Upload and select this file: checkstyle-None.xml.

After selecting this file as the Checkstyle configuration file, click Finish to save your work.

Use the Grading tab to find and then regrade your latest submission to your web log analyzer assignment. Did the static analysis errors go away?

For reference, the checks provided by the JavaTddPlugin’s default configuration are defined in checkstyle.xml.

SIGCSE 2009 Workshop