Car_Rental_Code_Coverage_with_Cobertura

Code Coverage with Cobertura

This example is based on the Car_Rental_Example. If you want work through this example, you need to follow these instructions first.

In this example, we add code coverage to the Car Rental Application. We then examine the results, make some changes and finish with a few conclusions.

Setup and Configuration

Cobertura does not currently come with a plugin, so in this example we’ll use Ant from within Eclipse. I’ll warn you that I’m not much of an Ant user, so if you’d like to make recommendations, please feel free: schuchert@yahoo.com.

Let’s get started:

Download

Download Cobertura from here. Note I downloaded version 1.8 for this example.
Extract the jar somewhere. I used c:\libs\, which created the directory C:\libs\cobertura-1.8.
Start Eclipse using the Car Rental workspace. If you used my directory names, it is C:\workspaces\CarRentalExample.

suite() method

Ant 1.6.5 does not play nice with JUnit 4.x, so I added a suite() method to each of my classes. Depending on when you downloaded this file, you already have those suite methods.

Ant Script

When you followed these instructions, you should have created a workspace with three projects:

CarRental
LoggingUtils
ToolConfiguration

Under CarRental there is an xml directory that contains two ant build files:

cobertura.xml
emma.xml

(By the way, let me give credit where it’s due, I got most of this from Cobertura Ant Task Reference.

Here’s the file so we can discuss it and configure it for your situation:

cobertura.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <project name="cobertura" default="coverage-report">
 
    <property name="cobertura.dir" value="C:/libs/cobertura-1.8" />
 
    <path id="cobertura.classpath">
       <fileset dir="${cobertura.dir}">
          <include name="cobertura.jar" />
          <include name="lib/**/*.jar" />
       </fileset>
    </path>
 
    <taskdef classpathref="cobertura.classpath" resource="tasks.properties" />
 
    <target name="init">
       <property name="base.dir" value=".." />
       <property name="cobertura.out.dir" value="${base.dir}/cobertura_results" />
       <property name="cobertura.datafile" value="${cobertura.out.dir}/cobertura.ser" />
 
       <delete dir="${cobertura.out.dir}" quiet="true" />
       <mkdir dir="${cobertura.out.dir}" />
 
       <property name="classes.dir" value="${cobertura.out.dir}/instrumented-classes" />
       <property name="testreport.dir" value="${cobertura.out.dir}/reports" />
       <property name="spring.jar" value="C:/libs/spring-framework-2.0-rc2/dist/spring.jar" />
       <property name="spring.lib" value="C:/libs/spring-framework-2.0-rc2/lib" />
       <property name="aspectj.lib" value="C:/libs/aspectj/lib" />
       <property name="loggingutil.dir" value="C:/workspaces/CarRentalExample/LoggingUtils" />
 
    </target>
 
    <target name="instrument" depends="init">
       <cobertura-instrument todir="${classes.dir}" datafile="${cobertura.datafile}">
          <classpath refid="cobertura.classpath" />
          <classpath location="${spring.lib}/log4j/log4j-1.2.13.jar" />
          <instrumentationClasspath>
             <pathelement location="${base.dir}/bin" />
          </instrumentationClasspath>
 
          <includeClasses regex="vehicle.*" />
          <excludeClasses regex="org.*" />
       </cobertura-instrument>
    </target>
 
    <target name="cover-test" depends="instrument">
       <mkdir dir="${testreport.dir}/junit" />
       <junit dir="${cobertura.out.dir}" maxmemory="512m" failureproperty="test.failure" printSummary="withOutAndErr" fork="true" showoutput="yes" forkmode="once" haltonerror="true">
          <formatter type="plain" />
          <classpath refid="cobertura.classpath" />
          <classpath location="${loggingutil.dir}/bin" />
          <classpath location="${classes.dir}" />
          <classpath location="${coberutra.lib}" />
          <classpath location="${aspectj.lib}/aspectjlib.jar" />
          <classpath location="${aspectj.lib}/aspectjrt.jar" />
          <classpath location="${aspectj.lib}/aspectjweaver.jar" />
          <classpath location="${spring.jar}" />
          <classpath location="${spring.lib}/jakarta-commons/commons-logging.jar" />
          <classpath location="${spring.lib}/log4j/log4j-1.2.13.jar" />
          <classpath location="${base.dir}/bin/" />
          <batchtest todir="${testreport.dir}/junit">
             <fileset dir="${base.dir}/bin/">
                <include name="**/*Test.class" />
             </fileset>
          </batchtest>
       </junit>
    </target>
 
    <target name="coverage-report" depends="cover-test">
       <cobertura-report destdir="${testreport.dir}" datafile="${cobertura.datafile}">
          <fileset dir="${base.dir}/src">
             <include name="**/*.java" />
          </fileset>
          <fileset dir="${base.dir}/test">
             <include name="**/*.java" />
          </fileset>
       </cobertura-report>
    </target>
 </project>

Execution

Assuming you’ve updated the cobertura.xml file and set all of the relevant properties for your environment, then do the following:

Right-click on CarRental/xml/cobertura.xml
Select Run As:Ant Build
Wait for a few seconds (about 5 - 10 in my case)
Note that this ant file adds a directory called cobertrua_results under the CarRental directory with the execution results. To see this (if you don’t automatically see it after executing this ant task), select CarRental, right-click and select refresh (or hit F5).

I considered adding the following line to cobertura.xml:

<eclipse.refreshLocal resourcePath="CarRental" depth="infinite"/>

This would force a refresh but it also requires that you run the ant script in the same VM as Eclipse.

Preliminary Analysis

With your directory refreshed, you’re ready to have a look at the output:

Expand the CarRental project.
Expand the cobertura_results directory.
Expand the reports directory.
Double click on index.xml (I’ve noticed that this sometimes fails when I’m using RAD. If this happens to you, just open this with your favorite browser).
Here’s a summary of my numbers by package:

Package	#Classes	Line Coverage	covered/total	Branch Coverage	covered/total	Complexity
All_Packages	88	85%	1680/1984	88%	120/136	1.3125
vehicle.component.rateplan	2	87%	256/295	100%	5/5	0
vehicle.component.rentalagreement	2	96%	73/76	100%	5/5	0
vehicle.component.vehicle	2	85%	66/78	89%	8/9	0
vehicle.component.vehicletype	2	86%	100/116	80%	4/5	0
vehicle.configuration	2	71%	22/31	100%	3/3	0
vehicle.domain	27	86%	503/587	73%	16/22	0
vehicle.exception	5	69%	9/13	N/A	N/A	1.0
vehicle.integration	8	87%	143/164	100%	2/2	1.0
vehicle.integration.inmemory	5	91%	140/154	96%	44/46	2.333
vehicle.reference	1	81%	22/27	100%	1/1	0
vehicle.type	13	67%	109/163	60%	6/10	0
vehicle.util	4	87%	33/38	100%	4/4	4.0
vehicle.validation	16	84%	204/242	92%	22/24	0

If we pay attention to just the line coverage, we see a range from 67% to 96%. Let’s work with just this value and try to “improve it”. The ultimate goal is 100% line coverage and 100% branch coverage. However, in practice getting this may take much longer than it is worth. Even so, we’ll strive for at least 90% or better in every package.

Let’s begin by working from the worst pacakge to the best package. This gives us the following packages (in order):

vehicle.type
vehicle.exception
vehicle.configuration
vehicle.reference
vehicle.validation
vehicle.component.vehicle
vehicle.component.vehicletype
vehicle.domain
vehicle.component.rateplan
vehicle.integration
vehicle.util
vehicle.integration.inmemory
vehicle.component.rentalagreement

Even though the last two packages already have 90% coverage, we’ll review them anyway.

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