Jenkins JaCoCo Plugin

To generate a report, you first need to ensure your Maven or Gradle build file is configured to output the JaCoCo .exec execution data file. Then, add the "Record JaCoCo coverage report" post-build action (or pipeline step `jacoco`) in your Jenkins job configuration. Point the plugin to the location of the .exec file and your class/source directories to render the report.

Line coverage measures the percentage of executable lines of code that have been exercised by your JUnit tests. Branch coverage, on the other hand, calculates the percentage of execution branches (like if/else conditions) that have been evaluated. The JaCoCo plugin tracks both metrics, allowing you to set quality gates that fail the build if coverage drops below a certain threshold.

This usually happens when the plugin cannot locate the .exec data file generated by your test execution or cannot match the compiled class files. You must ensure the path specified in the "Path to exec files" field accurately reflects where your build tool places the JaCoCo output. Additionally, verify that the tests are actually running before Jenkins attempts to record the coverage.

Yes, the plugin allows you to configure quality gates that will intentionally fail or mark the build as unstable based on coverage metrics. You can set specific thresholds for overall line coverage, branch coverage, or even the amount of new code introduced. This ensures developers cannot merge changes that lower the overall code health of the Java project.