NetBeans Code Coverage Plugin

Outline

In this tutorial you'll follow a short walkthrough for using the NetBeans Code Coverage Plugin named "TikiOne JaCoCoverage".

  • Introduction
  • Installing the plugin
  • Running the Tests
  • Viewing Coverage Results
  • Improving Coverage
  • Known Issues

Introduction

The NetBeans Code Coverage Plugin provides an interactive way to see testing coverage results within the NetBeans IDE. This enables developers to quickly identify the portions of Java code that aren't covered by their unit tests.  Of course you need to have tests in your project for it to work.

NOTE: There is a separate page for code coverage of Maven projects - MavenCodeCoverage

Demo Project

This tutorial offers a walkthrough that uses a demonstration NetBeans project.

Download and unzip the CodeCoverageDemo project into a local folder.

The tutorial provides screenshots so you can still see how the main features operate even if you choose not to follow the step-by-step walkthrough.

This walkthrough was created with NetBeans 7.3 on Ubuntu.

Install the plugin

If you haven't already install the plugin follow these simple steps.

From NetBeans menu select Tools > Plugins and wait for the Plugins dialog to appear.   Select the "Available Plugins" tab an type "coverage" in the Search box.  The TikiOne plugin appears in the left hand panel. 

plugin dialog

Click the checkbox next to the plugin name and click install.

 

Running the Tests

After you have opened the demo project expand the project node to see the files in the Source package. In the default package, open PigLatin.java.

Once the plugin is installed you will see a new menu item from the Project context menu "Test with JaCoCoverage".  Choosing this option will run the project with all the unit tests and gather coverage data.  The tests should pass.

Menu item for Test with JaCoCoverage

Viewing Coverage Results

Once the tests are completed a browser window will open automatically to display the coverage results.

results home page

Notice coverage of the package is 63%. Click on the link for the package "Default" to view its classes. Click on the "PigLatin" class to view its methods.  Click on the "convert(String)" method to view the code.

class results


Observe green highlighting in the results window. Notice the true branch of the 'if' statement is green, but the false branch is not. Specifically, lines 26 & 28 in the source are red. That's because the test didn't cause those lines to be executed.

Improving Coverage

Back in NetBeans, go to the Test package and open PigLatinTest.java.

Notice lines 11 and 12 are commented out. Those two lines will cause the false branch of the 'if' statement to execute.

Remove the slashes to uncomment those two lines.  

Once again run "Test with JaCoCoverage".

In the browser results window notice coverage is now 100%. 

Expand the results to view the PigLatin source and and observe the green highlighting now includes line 26 & 28.. (The 'else' statement is not green, apparently because the plugin doesn't consider it an executable statement.)

That's all there is to viewing code coverage of your tests!

Known Issues and Quirks

  • The plugin doesn't work with Maven-based projects, only Ant-based ones. (Bug 157946)
  • You can't obtain coverage from a single unit test only from the entire project tests. 
  • If you also have the Checkstyle plugin installed, checkstyle errors will hide the coverage highlighting. So fix the checkstyle errors and then you can see the coverage highlights.
  • If you have a class with only static methods, you can't get 100% coverage unless you also instantiate the class.
  • More issues are discussed in the User Comments on this page. 
  • On the plugin developer project page there is a statement that the plugin is no longer under active development.