Code Coverage using JUnit, JaCoCo and Sonar

For every code that's written in Java, it's always the right thing to "TEST". As part of testing process, we aim at covering maximum implementation lines possible. In order to measure the test coverage we rely on Code Coverage tools. Among the famous code coverage tools, JaCoCo is famous and is very easy to implement.

Below we will develop a very simple code, write test cases (unit tests and integration tests), attach project to SonarQube server and configure the maven JaCoCo plugin to generate code coverage reports.


We will use maven's quickstart archetype for creating project structure. Below is how it looks like:

Step 1: Simple coding in App.java

package go.eat.learn.springboot.example;


public class App 
{   
    public void sayFruitOrVegetable(String input){
     
     if(input.equalsIgnoreCase("apple")){
      System.out.println("It's a fruit");
     }else{
      System.out.println("It's a vegetable");
     }
     
     
    }
}

Step 2: Unit test code in AppTest.java

 package go.eat.learn.springboot.example;

import org.junit.Test;

public class AppTest {
 
 @Test
 public void testSayFruitOrVegetable() {
  App app = new App();
  app.sayFruitOrVegetable("apple");
 }
}

Step 3: Integration test coding in AppIT.java

package go.eat.learn.springboot.example;

import org.junit.Test;

public class AppIT {
 
 @Test
 public void testSayFruitOrVegetable() {
  App app = new App();
  app.sayFruitOrVegetable("broccoli");
 }

}

Step 4: Set up SonarQube and integrate with eclipse - refer our earlier post
http://www.goeatlearn.com/2015/06/using-sonar-with-eclipse.html

Step 5: Configure pom.xml

Below is entire pom.xml configuration provided for clarity.
Main points to note are:
           a. Configuring sonar properties
           b. Mentioning JaCoCo plugin unit tests end with *Test.java and integration tests end with *IT.java
           c. Configuing m2e plugin to ignore JaCoCo life cycle execution errors (you'll notice :
Plugin execution not covered by lifecycle configuration: org.jacoco:jacoco-maven-plugin. Add exclusions in m2e plugin to ignore it)
           d. Once you configure m2e plugin, still you'll see "x" mark in eclipse's pom - do not worry. Do a maven build by passing  "clean install sonar:sonar" goal - it should be successful

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 <modelVersion>4.0.0</modelVersion>

 <groupId>go.eat.learn</groupId>
 <artifactId>springboot.example</artifactId>
 <version>0.0.1-SNAPSHOT</version>
 <packaging>jar</packaging>

 <name>springboot.example</name>
 <url>http://maven.apache.org</url>

 <properties>
  <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  <jacoco.it.execution.data.file>${project.build.directory}/coverage-reports/jacoco-it.exec</jacoco.it.execution.data.file>
  <sonar.core.codeCoveragePlugin>jacoco</sonar.core.codeCoveragePlugin>
  <sonar.jacoco.reportPath>${project.build.directory}/coverage-reports/jacoco-ut.exec</sonar.jacoco.reportPath>
  <sonar.jacoco.itReportPath>${project.build.directory}/coverage-reports/jacoco-it.exec</sonar.jacoco.itReportPath>
  <sonar.surefire.reportsPath>${project.build.directory}/surefire-reports</sonar.surefire.reportsPath>
  <maven.surefire.plugin.version>2.18.1</maven.surefire.plugin.version>
  <maven.failsafe.plugin.version>2.18.1</maven.failsafe.plugin.version>
 </properties>

 <dependencies>
  <dependency>
   <groupId>junit</groupId>
   <artifactId>junit</artifactId>
   <version>4.8.1</version>
   <scope>test</scope>
  </dependency>
 </dependencies>

 <build>
  <plugins>
   <!-- Java Code Coverage Start -->
   <plugin>
    <groupId>org.jacoco</groupId>
    <artifactId>jacoco-maven-plugin</artifactId>
    <version>0.6.4.201312101107</version>
    <executions>
     <execution>
      <id>prepare-unit-test-agent</id>
      <goals>
       <goal>prepare-agent</goal>
      </goals>
      <configuration>

       <destFile>${sonar.jacoco.reportPath}</destFile>
       <propertyName>surefireArgLine</propertyName>
      </configuration>
     </execution>
     <execution>
      <id>generate-unit-test-report</id>
      <goals>
       <goal>report</goal>
      </goals>
      <configuration>
       <!-- Supplying data file of JaCoCo Unit Tests is must -->
       <dataFile>${sonar.jacoco.reportPath}</dataFile>
      </configuration>
     </execution>
     <execution>
      <id>prepare-integration-test-agent</id>
      <goals>
       <goal>prepare-agent-integration</goal>
      </goals>
      <configuration>
       <!-- Same explanation as UT's -->
       <destFile>${sonar.jacoco.itReportPath}</destFile>
       <propertyName>surefireArgLine</propertyName>
      </configuration>
     </execution>
     <execution>
      <id>generate-integration-test-report</id>
      <goals>
       <goal>report-integration</goal>
      </goals>
      <configuration>
       <!-- Same explanation as UT's -->
       <dataFile>${sonar.jacoco.itReportPath}</dataFile>
      </configuration>
     </execution>
    </executions>
   </plugin>

   <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-surefire-plugin</artifactId>
    <!-- Version declaration for surefire is not mandatory at this place 
     - present for reference purpose -->
    <version>${maven.surefire.plugin.version}</version>
    <executions>
     <execution>
      <id>run-unit-tests</id>
      <goals>
       <goal>test</goal>
      </goals>
      <configuration>
       <argLine>-Xmx1024m -XX:MaxPermSize=256m ${surefireArgLine}</argLine>
       <skipTests>${skip.unit.tests}</skipTests><!-- Defaults to false -->
       <excludes>
        <!-- By default Sonar's JaCoCo expects Integration Tests to be *IT.java 
         or *ITCase.java -->
        <exclude>**/IT*.java</exclude>
       </excludes>
      </configuration>
     </execution>
    </executions>
   </plugin>

   <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-failsafe-plugin</artifactId>
    <version>${maven.failsafe.plugin.version}</version>
    <executions>
     <execution>
      <id>run-integration-tests</id>
      <goals>
       <goal>integration-test</goal>
       <goal>verify</goal>
      </goals>
      <configuration>
       <argLine>-Xmx1024m -XX:MaxPermSize=256m ${surefireArgLine}</argLine>
       <skipTests>${skip.integration.tests}</skipTests><!-- Defaults to false -->
       <excludes>
        <!-- By default Sonar's JaCoCo expects Unit tests to be **Test.java -->
        <exclude>**/Test*.java</exclude>
       </excludes>
      </configuration>
     </execution>
    </executions>
   </plugin>


   <!--This plugin's configuration is used to store Eclipse m2e settings 
    only. It has no influence on the Maven build itself. -->
   <plugin>
    <groupId>org.eclipse.m2e</groupId>
    <artifactId>lifecycle-mapping</artifactId>
    <version>1.0.0</version>
    <configuration>
     <lifecycleMappingMetadata>
      <pluginExecutions>
       <pluginExecution>
        <pluginExecutionFilter>
         <groupId>org.jacoco</groupId>
         <artifactId>jacoco-maven-plugin</artifactId>
         <versionRange>[0.5,)
         </versionRange>
         <goals>
          <goal>prepare-agent</goal>
         </goals>
        </pluginExecutionFilter>
        <action>
         <!-- m2e doesn't know what to do with jacoco, let's ignore it or 
          annoying error markers appear see http://wiki.eclipse.org/M2E_plugin_execution_not_covered -->
         <ignore></ignore>
        </action>
       </pluginExecution>
      </pluginExecutions>
     </lifecycleMappingMetadata>
    </configuration>
   </plugin>
   <!-- Java Code Coverage End -->
  </plugins>
 </build>
</project>

Step 6: Run Maven goal "clean install sonar:sonar"

Step 7: Launch sonar in browser at http://localhost:9000 and log in as admin

Step 8: Select your project on main dashboard

Step 9: Select "More" -> "Manage Dashboards"

Step 10: Select "Integration Tests Coverage" widget as shown below

Step 11: Select "Back to Dashboard"

Step 12: You are done, you'll see Integration Tests coverage and Unit Test coverage as below:

Play around by clicking the coverage percentage, you'll get detailed reports on line coverage for each java file

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