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comparison content/Maven/sonar-vs-jacoco-vs-surefire.md @ 103:6aa2fa328a94
New blog post on sonar and maven
| author | Dirk Olmes <dirk.olmes@codedo.de> |
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| date | Tue, 12 May 2020 08:30:22 +0200 |
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| 102:94bbe517a174 | 103:6aa2fa328a94 |
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| 1 Title: Generating test coverage for Sonar with maven, surefire and jacoco | |
| 2 Date: 2020-05-11 | |
| 3 Lang: en | |
| 4 | |
| 5 At work we're using [Sonar](https://www.sonarqube.org) to keep our code quality under control. One integral part of code quality is test coverage and Sonar offers coverage metrics in the UI. However, the [Sonar docs on code coverage](https://docs.sonarqube.org/latest/analysis/coverage/) are a bit sparse (at best) and don't tell you the exact steps to run for getting coverage with a Maven build. | |
| 6 | |
| 7 With a bit of googling I was eventually able to find the correct steps to get coverage. The key to success is the [Jacoco Maven plugin](https://www.eclemma.org/jacoco/trunk/doc/maven.html). In a first Maven execution we let jacoco record coverage statistics while running the unit tests: | |
| 8 | |
| 9 :::bash | |
| 10 mvn clean org.jacoco:jacoco-maven-plugin:prepare-agent install | |
| 11 | |
| 12 In the build log you see the jacoco-maven-plugin in action (we'll get back to this in a while): | |
| 13 | |
| 14 [INFO] --- jacoco-maven-plugin:0.8.5:prepare-agent (default-cli) @ sonar-code-coverage --- | |
| 15 [INFO] argLine set to -javaagent:/.m2/repository/org/jacoco/org.jacoco.agent/0.8.5/org.jacoco.agent-0.8.5-runtime.jar=destfile=/sonar-code-coverage/target/jacoco.exec | |
| 16 | |
| 17 Then in a second Maven execution we'll pick up those coverage statistics and convert them to XML so that Sonar can include them in its analysis: | |
| 18 | |
| 19 :::bash | |
| 20 mvn org.jacoco:jacoco-maven-plugin:report org.sonarsource.scanner.maven:sonar-maven-plugin:sonar | |
| 21 | |
| 22 **Hooray! Coverage info in Sonar.** | |
| 23 | |
| 24 The trouble starts when you need to pass custom arguments through surefire down to the JVM that will run the tests. This is done through the `<argLine>` configuration parameter of maven-surefire-plugin: | |
| 25 | |
| 26 :::xml | |
| 27 <plugin> | |
| 28 <groupId>org.apache.maven.plugins</groupId> | |
| 29 <artifactId>maven-surefire-plugin</artifactId> | |
| 30 <configuration> | |
| 31 <argLine>-Xmx128m</argLine> | |
| 32 </configuration> | |
| 33 </plugin> | |
| 34 | |
| 35 Looking back at the output of jacoco-maven-plugin above you'll notice that we're setting exactly the same `<argLine>` parameter as jacoco-maven-plugin does. If you don't take extra steps only one configuration can win - and that's the configuration you put into your pom. You have to run `mvn -X` to actually see this, though: | |
| 36 | |
| 37 [DEBUG] Forking command line: /bin/sh -c cd /sonar-code-coverage && /opt/openjdk-bin-8.252_p09/jre/bin/java -Xmx128m -jar /sonar-code-coverage/target/surefire/surefirebooter9099169912642065145.jar /sonar-code-coverage/target/surefire 2020-05-12T07-39-04_225-jvmRun1 surefire3709014631518520641tmp surefire_01706858247537265191tmp | |
| 38 | |
| 39 Note how the `-javaagent:...` argLine is not included in the command line arguments of the JVM that's forked to run the tests. | |
| 40 | |
| 41 A way to fix this is through creative use of Maven build properties. Configure the jacoco-maven-plugin to set a different property than `argLine`: | |
| 42 | |
| 43 :::xml | |
| 44 <plugin> | |
| 45 <groupId>org.jacoco</groupId> | |
| 46 <artifactId>jacoco-maven-plugin</artifactId> | |
| 47 <configuration> | |
| 48 <propertyName>surefire.argLine.sonar</propertyName> | |
| 49 </configuration> | |
| 50 </plugin> | |
| 51 | |
| 52 Next, configure maven-surefire-plugin to include that property into its `<argLine>`: | |
| 53 | |
| 54 :::xml | |
| 55 <plugin> | |
| 56 <groupId>org.apache.maven.plugins</groupId> | |
| 57 <artifactId>maven-surefire-plugin</artifactId> | |
| 58 <configuration> | |
| 59 <argLine>-Xmx128m @{surefire.argLine.sonar}</argLine> | |
| 60 </configuration> | |
| 61 </plugin> | |
| 62 | |
| 63 Note that you have to use [late evaluation](http://maven.apache.org/surefire/maven-surefire-plugin/test-mojo.html#argLine) of the property because it's not present when the Maven reactor starts but only after jacoco-maven-plugin has run. | |
| 64 | |
| 65 Just one last hack is required to make the build work even if you don't run jacoco coverage as part of your build. Specify an empty property `surefire.argLine.sonar` in your project's properties so that it always exists and can be expanded. | |
| 66 | |
| 67 For further reference I've put [a demo project up on github](https://github.com/dirk-olmes/sonar-code-coverage). |