Refactoring Unit Test Stage

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.

Table of Contents

• Pipeline Configuration with Kubernetes Agent
• Sequential Unit Testing and Coverage
• Parallel Testing Across Node.js Versions
  • Pipeline Snippet
  • Agent and Container Matrix
• Diagnosing the Node.js 20 Failure
• Installing Dependencies in Node.js 20 Stage
• Next Steps and Further Reading

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')
  }
  // ...
}

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.

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

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'
        }
      }
    }
  }
}

Agent and Container Matrix

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

Installing Dependencies in Node.js 20 Stage

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'
  }
}

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.

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+).

Links and References

• Jenkins Kubernetes Plugin
• Node.js Docker Official Images
• Jenkins Pipeline Syntax
• Mocha Testing Framework

That completes the refactoring of the Unit Test stage to support parallel testing across multiple Node.js versions.