JaCoCo Java Code Coverage Library

JaCoCo is a free Java code coverage library distributed under the Eclipse Public License. Check the project homepage for downloads, documentation and feedback.

Please use our mailing list for questions regarding JaCoCo which are not already covered by the extensive documentation.

Note: We do not answer general questions in the project's issue tracker. Please use our mailing list for this.

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Features

Method filtration for *.scala files

On the fly logic for removing methods. All methods which are not part of their source file are removed from JaCoCo bundle.

Motivation

JaCoCo report contains big amount of inherited methods which is not needed/expected to cover by tests.

Inputs:

• jacoco.exec file (as JaCoCo bundle data source)
• built class files (as JaCoCo bundle data source)
• source class files (as source of truth for method filtration)

Outputs:

• reduced JaCoCo bundle as a source for report generation

Configuration

<execution>
    <id>jacoco-report</id>
    <goals>
        <goal>report</goal>
    </goals>
    <configuration>
        <title>${project.name} - ${scala.version}</title>
        <doMethodFiltration>true</doMethodFiltration>
        <doScalaMethodFiltration>true</doScalaMethodFiltration>
        <doManualScalaMethodFiltration>true</doManualScalaMethodFiltration>
        <srcRootDir>src/main/scala</srcRootDir>
        <methodExcludes>
            <exclude>com/package/patk/Classname@methodName</exclude>
        </methodExcludes>
    </configuration>
</execution>

Classes

• org.jacoco.core.analysis.CoverageBundleMethodFilterConst.java
• org.jacoco.core.analysis.CoverageBundleMethodFilterScalaImpl.java
• org.jacoco.core.analysis.ClassCondensate.java
• org.jacoco.core.analysis.CoverageBundleMethodFilterScalaImplTest.java

Possible log output messages

• KEPT_by_SKIP_CLASS_NAME
• KEPT_by_SKIP_METHOD_NAME
• KEPT_by_EXISTING
• KEPT_by_EXCEPTION
• REMOVED_by_SKIP_CLASS_NAME_INIT_METHOD
• REMOVED - not found in class file.
• REMOVED - not found in classCondensate.
• REMOVED_BY_MANUAL_EXCLUDE - manually defined to remove from report

Tips

Implemented filtration logic does not contain all possible scala code combinations. All class elements are removed if they are not found in source files. This can lead to unexpected removes of logic. Suggestion for usage:

• Generate two JaCoCo reports: switched on/off method filtration.
• Do comparison of results.
• If you identify missing method after filtration collect inputs and provide them to us to improved logic.

Known issues

• When used on project with Github Action madrapps/jacoco-report@v1.3 then overall % can be different. Detected 5% difference.

How to use locally

Until Scala method filtering solution will be available in official library. You can use this workaround.

How to get library with filtering logic

• Checkout this repository.
• Call mvn install in repository root dir.
• New snapshots should be available on path $HOME/.m2/repository/za/co/absa/jacoco/*

How to use library in maven project

• Optional: add new version property in your pom.xml file

    <jacoco.version>0.8.10</jacoco.version>

• add new profile section in your pom.xml file

<profile>
    <id>code-coverage</id>
    <properties>
        <scalatest.argLine>${default.scalatest.argLine} ${argLine}</scalatest.argLine>
        <skip.integration.tests>false</skip.integration.tests>
        <skip.unit.tests>false</skip.unit.tests>
    </properties>
    <build>
        <plugins>
            <plugin>
                <groupId>za.co.absa.jacoco</groupId>
                <artifactId>jacoco-maven-plugin</artifactId>
                <version>${jacoco.version}</version>
                <executions>
                    <execution>
                        <id>jacoco-prepare-agent</id>
                        <goals>
                            <goal>prepare-agent</goal>
                        </goals>
                    </execution>
                    <execution>
                        <id>jacoco-report</id>
                        <goals>
                            <goal>report</goal>
                        </goals>
                        <configuration>
                            <title>${project.name} - ${scala.version}</title>
                            <doMethodFiltration>true</doMethodFiltration>
                            <doScalaMethodFiltration>true</doScalaMethodFiltration>
                            <doManualScalaMethodFiltration>true</doManualScalaMethodFiltration>
                            <methodExcludes>
                                <exclude>com/path/ClassName@methodName</exclude>
                            </methodExcludes>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</profile>

• to activate JaCoCo report generation call mvn clean verify -Pcode-coverage

How to use library in sbt project

• For JaCoCo with sbt continue with steps in project AbsaOSS/sbt-jacoco