Code coverage reports in Jenkins - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Jenkins Pipeline: Code Coverage Report Generation

Given this Jenkins pipeline snippet, what will be the output after running the jacoco step?

Jenkins

pipeline {
  agent any
  stages {
    stage('Build') {
      steps {
        echo 'Building project...'
      }
    }
    stage('Test') {
      steps {
        echo 'Running tests...'
      }
    }
    stage('Code Coverage') {
      steps {
        jacoco execPattern: '**/target/*.exec', classPattern: '**/classes', sourcePattern: '**/src/main/java'
      }
    }
  }
}

A The pipeline runs but does not generate any coverage report because no test execution is specified.

B The pipeline generates a JaCoCo code coverage report and archives it in Jenkins for visualization.

C The pipeline fails because the <code>jacoco</code> step is not recognized in Jenkins pipelines.

D The pipeline generates a test report but no code coverage report.

💡 Hint

The jacoco step in Jenkins pipelines is used to collect and publish code coverage reports.

The jacoco step collects coverage data from the specified exec files and generates a report Jenkins can display. It requires the JaCoCo plugin installed.

❓ Troubleshoot

intermediate

Troubleshooting Missing Coverage Data in Jenkins

A Jenkins job runs tests and uses JaCoCo for coverage, but the coverage report shows 0% coverage. What is the most likely cause?

A The JaCoCo exec files were not generated because tests did not run with the JaCoCo agent enabled.

B The Jenkins workspace was cleaned before running tests, deleting coverage data.

C The <code>jacoco</code> step was placed before the test execution stage in the pipeline.

D The Jenkins server does not have enough memory to generate the coverage report.

💡 Hint

Coverage data depends on tests running with the coverage agent active.

If tests run without the JaCoCo agent, no coverage data is collected, resulting in 0% coverage report.

❓ Configuration

advanced

Configuring Jenkins to Fail Build on Low Coverage

Which Jenkins pipeline snippet correctly fails the build if code coverage is below 80% using JaCoCo plugin?

A jacoco execPattern: '**/target/*.exec', classPattern: '**/classes', sourcePattern: '**/src/main/java', changeBuildStatus: true, minimumInstructionCoverage: '80'

B jacoco execPattern: '**/target/*.exec', classPattern: '**/classes', sourcePattern: '**/src/main/java', minimumInstructionCoverage: 80, failBuild: true

C jacoco execPattern: '**/target/*.exec', classPattern: '**/classes', sourcePattern: '**/src/main/java', changeBuildStatus: true, minimumInstructionCoverage: '80%'

D jacoco execPattern: '**/target/*.exec', classPattern: '**/classes', sourcePattern: '**/src/main/java', failBuildOnLowCoverage: true, minimumCoverage: 80

💡 Hint

Check the official JaCoCo plugin documentation for correct parameter names and types.

The changeBuildStatus parameter set to true enables build failure on coverage below thresholds. The threshold values are strings without % sign.

🔀 Workflow

advanced

Best Workflow to Collect Coverage from Multiple Modules

You have a multi-module Maven project. How should you configure Jenkins to collect JaCoCo coverage reports from all modules correctly?

A Run tests only in the root module and use <code>jacoco</code> step with execPattern '**/target/*.exec' to collect coverage.

B Run tests separately for each module and call <code>jacoco</code> step individually for each module's exec file.

C Run <code>mvn clean install</code> and rely on Jenkins to auto-detect coverage files without specifying patterns.

D Run <code>mvn clean verify</code> at root, then use <code>jacoco</code> step with execPattern '**/target/*.exec' to collect all coverage files.

💡 Hint

Maven multi-module builds generate coverage files in each module's target directory.

Running mvn clean verify at root runs tests in all modules. Using a wildcard execPattern collects all coverage files for combined report.

✅ Best Practice

expert

Ensuring Accurate Coverage Reports in Jenkins Pipelines

Which practice ensures the most accurate and reliable code coverage reports in Jenkins pipelines using JaCoCo?

A Run tests without JaCoCo agent and rely on Jenkins to generate coverage from compiled classes.

B Run <code>jacoco</code> step before tests to initialize coverage collection, then run tests normally.

C Run tests with JaCoCo agent enabled, archive exec files as artifacts, and run <code>jacoco</code> step after tests complete.

D Run tests with JaCoCo agent but do not archive exec files; just run <code>jacoco</code> step to generate report.

💡 Hint

Coverage data must be collected during test execution and preserved for reporting.

Enabling JaCoCo agent during tests collects coverage data. Archiving exec files ensures data is available for report generation after tests.