Introduction to lcov-parse

lcov-parse is a powerful tool designed to provide detailed insights into code coverage reports. It parses LCOV coverage data and transforms it into an accessible and usable format. Whether you are a developer looking to optimize your unit tests or a CI/CD engineer aiming to integrate comprehensive code coverage reports into your build pipeline, lcov-parse offers a range of APIs to suit your needs.

API Examples

Parsing LCOV Data

This is the primary function of lcov-parse – transforming raw LCOV data into a structured JavaScript object.

  const lcovParse = require('lcov-parse');
  const fs = require('fs');

  fs.readFile('path/to/coverage/lcov.info', 'utf8', (err, data) => {
    if (err) throw err;
    lcovParse(data, (err, result) => {
      if (err) throw err;
      console.log(result);
    });
  });

Handling Parsed Data

Once the LCOV data is parsed, you can use the resulting object to suit your needs.

  lcovParse(data, (err, result) => {
    if (err) throw err;

    result.forEach(file => {
      console.log(`File: ${file.file}`);
      file.lines.details.forEach(line => {
        console.log(`Line ${line.line}: ${line.hit} hits`);
      });
    });
  });

Filtering Files

Sometimes you might want to process only specific files from the coverage report.

  lcovParse(data, (err, result) => {
    if (err) throw err;

    const filtered = result.filter(file => file.file.includes('src/'));
    console.log(filtered);
  });

Integrating with CI/CD

Integrate parsed LCOV data into your CI/CD pipeline for automated coverage reports.

  const {exec} = require('child_process');

  exec('npm test', (err, stdout, stderr) => {
    if (err) {
      console.error(`Error executing tests: ${err}`);
      return;
    }

    fs.readFile('coverage/lcov.info', 'utf8', (err, data) => {
      if (err) throw err;
      
      lcovParse(data, (err, result) => {
        if (err) throw err;
        // Upload or handle parsed coverage data
        console.log(result);
      });
    });
  });

Application Example

Here’s a simple Node.js application that leverages lcov-parse to provide an endpoint for code coverage insights.

  const express = require('express');
  const fs = require('fs');
  const lcovParse = require('lcov-parse');
  const app = express();
  const port = 3000;

  app.get('/coverage', (req, res) => {
    fs.readFile('coverage/lcov.info', 'utf8', (err, data) => {
      if (err) {
        res.status(500).send('Failed to read coverage data');
        return;
      }

      lcovParse(data, (err, result) => {
        if (err) {
          res.status(500).send('Failed to parse coverage data');
          return;
        }

        res.json(result);
      });
    });
  });

  app.listen(port, () => {
    console.log(`Coverage app listening at http://localhost:${port}`);
  });

With lcov-parse, you can transform your LCOV reports into actionable data that can drive improvements in your codebase. The flexibility and ease of use make it ideal for integration into various stages of your development and deployment pipelines.

For more detailed information, visit the official documentation.

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