maven jacoco: not generating code coverage report

Question

I am trying to setup jacoco for my project's code coverage

My project is based on Java 1.8

Here is how things look in my project's pom.xml

    <plugin>
        <groupId>org.jacoco</groupId>
        <artifactId>jacoco-maven-plugin</artifactId>
        <version>0.5.10.201208310627</version>
        <configuration>
            <output>file</output>
            <append>true</append>
        </configuration>
        <executions>
            <execution>
                <id>jacoco-initialize</id>
                <goals>
                    <goal>prepare-agent</goal>
                </goals>
            </execution>
            <execution>
                <id>jacoco-site</id>
                <phase>verify</phase>
                <goals>
                    <goal>report</goal>
                </goals>
            </execution>
        </executions>
    </plugin>  

Then I run mvn test and see the following

$ mvn test
[INFO] Scanning for projects...
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building pennyapp 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] --- jacoco-maven-plugin:0.5.10.201208310627:prepare-agent (jacoco-initialize) @ pennyapp ---
[INFO] argLine set to -javaagent:/Users/harit/.m2/repository/org/jacoco/org.jacoco.agent/0.5.10.201208310627/org.jacoco.agent-0.5.10.201208310627-runtime.jar=destfile=/Users/harit/code/idea/pennyapp/target/jacoco.exec,append=true,output=file
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ pennyapp ---
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] Copying 1 resource
[INFO] 
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ pennyapp ---
[INFO] Changes detected - recompiling the module!
[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
[INFO] Compiling 1 source file to /Users/harit/code/idea/pennyapp/target/classes
[INFO] 
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ pennyapp ---
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] skip non existing resourceDirectory /Users/harit/code/idea/pennyapp/src/test/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.1:testCompile (default-testCompile) @ pennyapp ---
[INFO] Changes detected - recompiling the module!
[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
[INFO] Compiling 1 source file to /Users/harit/code/idea/pennyapp/target/test-classes
[INFO] 
[INFO] --- maven-surefire-plugin:2.17:test (default-test) @ pennyapp ---
[INFO] Surefire report directory: /Users/harit/code/idea/pennyapp/shippable/testresults
[INFO] Using configured provider org.apache.maven.surefire.junit4.JUnit4Provider

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
objc[13225]: Class JavaLaunchHelper is implemented in both /Library/Java/JavaVirtualMachines/jdk1.8.0_05.jdk/Contents/Home/jre/bin/java and /Library/Java/JavaVirtualMachines/jdk1.8.0_05.jdk/Contents/Home/jre/lib/libinstrument.dylib. One of the two will be used. Which one is undefined.
Running HelloTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.1 sec - in HelloTest

Results :

Tests run: 1, Failures: 0, Errors: 0, Skipped: 0

[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 4.523 s
[INFO] Finished at: 2014-08-19T17:56:33-07:00
[INFO] Final Memory: 10M/119M
[INFO] ------------------------------------------------------------------------

and then I run mvn jacoco:report and I see

$ mvn jacoco:report
[INFO] Scanning for projects...
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building pennyapp 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] --- jacoco-maven-plugin:0.5.10.201208310627:report (default-cli) @ pennyapp ---
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.176 s
[INFO] Finished at: 2014-08-19T17:56:51-07:00
[INFO] Final Memory: 11M/112M
[INFO] ------------------------------------------------------------------------

Then I look at target/site/jacoco/index.html and see the following

Question
- What is incorrect in the configuration?
- How can I generate report?

Thanks

Answer 1

Any particular reason why you are using an outdated version of the JaCoCo plugin? For Java 8 support, you have to use at least version 0.7.0 (see changelog).

In your configuration, the report goal is bound to the verify phase, so running mvn test won't generate any report because it does not run the verify phase (test phase comes before verify). You have to use mvn verify to execute tests and generate the report.

The JaCoCo project provides example Maven configurations. You can try "this POM file for a JAR project runs JUnit tests under code coverage and creates a coverage report".

Answer 2

JaCoco Maven Plugin is overriding Surefire argLine, in case you also need to override argLine, be sure to keep argLine variable:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-surefire-plugin</artifactId>
  <version>2.19.1</version>
  <configuration>
    <argLine>-Xmx1024M ${argLine}</argLine> 
  </configuration>
</plugin>

Note you can change this property name, as describe in the jacoco plugin documentation.

Answer 3

This worked for me:

mvn clean install
mvn site

Even though the minimum code coverage was not met and mvn clean install failed, the mvn site build succeeded and created the coverage report at:

.../target/site/jacoco/index.html