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In this tutorial, we’ll refactor the Unit Test stage of a Jenkins pipeline to run tests across multiple Node.js versions—18, 19, and 20—using Kubernetes agents and Docker containers. This approach improves reliability and ensures compatibility before merging changes.

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Table of Contents

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Pipeline Configuration with Kubernetes Agent

Below is an excerpt from the original Jenkinsfile that configures a Kubernetes agent, Node.js tool, and necessary environment variables: 
@Library('dasher-trusted-shared-library@featureTrivyScan') _
pipeline {
  agent {
    kubernetes {
      cloud 'dasher-prod-k8s-us-east'
      yamlFile 'k8s-agent.yaml'
      defaultContainer 'node-18'
    }
  }
  tools {
    nodejs 'nodejs-22-6-0'
  }
  environment {
    MONGO_URI        = "mongodb://srv-cluster.d83jj.mongodb.net/superData"
    MONGO_DB_CREDS   = credentials('mongo-db-credentials')
    MONGO_USERNAME   = credentials('mongo-db-username')
    MONGO_PASSWORD   = credentials('mongo-db-password')
  }
  // ...
}
Adjust yamlFile and defaultContainer to match your Kubernetes Pod specification.

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Sequential Unit Testing and Coverage

Originally, the pipeline ran Unit Testing and Code Coverage sequentially on Node.js 18: 
stage('Unit Testing') {
  options { retry(2) }
  steps {
    sh 'node -v'
    sh 'npm test'
  }
}

stage('Code Coverage') {
  steps {
    catchError(buildResult: 'SUCCESS',
               message: 'Coverage will be fixed in future releases',
               stageResult: 'UNSTABLE') {
      sh 'node -v'
      sh 'npm run coverage'
    }
  }
}
While straightforward, this setup doesn’t validate compatibility with newer Node.js versions.

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Parallel Testing Across Node.js Versions

To ensure your application works on Node.js 18, 19, and 20, we can run tests in parallel branches. This refactoring includes:
  • Installing dependencies once on the Kubernetes agent
  • Running dependency scanning (e.g., Snyk, Trivy)
  • Testing in parallel across multiple Node.js versions
  • Aggregating code coverage

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Pipeline Snippet

pipeline {
  agent {
    kubernetes {
      cloud 'dasher-prod-k8s-us-east'
      yamlFile 'k8s-agent.yaml'
      defaultContainer 'node-18'
    }
  }
  tools {
    nodejs 'nodejs-22-6-0'
  }
  environment {
    MONGO_URI          = "mongodb+srv://supercluster.d83jj.mongodb.net/superData"
    MONGO_DB_CREDS     = credentials('mongo-db-credentials')
    MONGO_USERNAME     = credentials('mongo-db-username')
    MONGO_PASSWORD     = credentials('mongo-db-password')
    SONAR_SCANNER_HOME = tool 'sonarqube-scanner-610'
    GITEA_TOKEN        = credentials('gitea-api-token')
  }
  options {
    disableResume()
    disableConcurrentBuilds(abortPrevious: true)
  }
  stages {
    stage('Installing Dependencies') {
      options { timestamps() }
      steps {
        sh 'node -v'
        sh 'npm install --no-audit'
      }
    }

    stage('Dependency Scanning') {
      parallel {
        // e.g., Trivy, Snyk, OWASP Dependency Check
      }
    }

    stage('Unit Testing') {
      parallel {
        stage('NodeJS 18') {
          options { retry(2) }
          steps {
            sh 'node -v'
            sh 'npm test'
          }
        }

        stage('NodeJS 19') {
          options { retry(2) }
          steps {
            container('node-19') {
              // Sleep to avoid port conflicts on shared volumes
              sh 'sleep 10s'
              sh 'node -v'
              sh 'npm test'
            }
          }
        }

        stage('NodeJS 20') {
          agent {
            docker { image 'node:20-alpine' }
          }
          options { retry(2) }
          steps {
            // npm install will be added here
            sh 'node -v'
            sh 'npm test'
          }
        }
      }
    }

    stage('Code Coverage') {
      steps {
        catchError(buildResult: 'SUCCESS',
                   message: 'Coverage will be fixed in future releases',
                   stageResult: 'UNSTABLE') {
          sh 'node -v'
          sh 'npm run coverage'
        }
      }
    }
  }
}

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Agent and Container Matrix

StageEnvironmentContainer/AgentPurpose
DependenciesKubernetes Podnode-18Install node_modules via npm install
ScanningKubernetes Podnode-18Security and license scanning
NodeJS 18Kubernetes Podnode-18Default Node.js
NodeJS 19Kubernetes Podnode-19 containerVerify compatibility with v19
NodeJS 20Docker-in-Docker Podnode:20-alpine DockerValidate on latest LTS
CoverageKubernetes Podnode-18Generate and publish code coverage

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Diagnosing the Node.js 20 Failure

After pushing the refactored Jenkinsfile, the NodeJS 20 branch failed: 
+ node -v
v20.18.0
+ npm test
> mocha app-test.js --timeout 10000 --reporter mocha-junit-reporter --exit
sh: mocha: not found
script returned exit code 127
The Docker container node:20-alpine starts with a clean filesystem—it doesn’t have your node_modules. Always install dependencies inside each container or agent before running tests.

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Installing Dependencies in Node.js 20 Stage

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Option 1: Inline npm install

Add npm install directly before running tests in the NodeJS 20 branch: 
stage('NodeJS 20') {
  agent {
    docker { image 'node:20-alpine' }
  }
  options { retry(2) }
  steps {
    sh 'npm install'
    sh 'node -v'
    sh 'npm test'
  }
}

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Option 2: Separate Install Step in Parallel Stage

Alternatively, include installation as part of the Unit Testing parallel stage: 
stage('Unit Testing') {
  parallel {
    // NodeJS 18 and 19 as before...

    stage('NodeJS 20') {
      agent {
        docker { image 'node:20-alpine' }
      }
      options { retry(2) }
      steps {
        sh 'npm install'
        sh 'node -v'
        sh 'npm test'
      }
    }
  }
}
Both ensure that each parallel branch has its own node_modules prior to execution.

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Next Steps and Further Reading

  • Explore adding test result archiving with junit plugin.
  • Integrate SonarQube for code quality reporting.
  • Consider dynamic matrix stages for other runtimes (e.g., Node.js 21+).
That completes the refactoring of the Unit Test stage to support parallel testing across multiple Node.js versions.

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