Introduction to lcov-parse

lcov-parse is a powerful tool for parsing LCOV coverage data, simplifying the process of analyzing code coverage reports generated by various testing frameworks. It provides a comprehensive set of APIs for extracting meaningful data from LCOV files, facilitating better test coverage visualization and reporting.

API Examples

Parsing an LCOV File

The core functionality of lcov-parse is to parse a given LCOV file. Here’s how you can do it:

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

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

Extracting Coverage Data

Once the LCOV file is parsed, you can extract various types of coverage data:

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

  const lcovData = '...'; // LCOV file data
  lcovParse(lcovData, (err, data) => {
      if (err) throw err;

      data.forEach(fileCov => {
          console.log(`File: ${fileCov.file}`);
          console.log(`Lines Covered: ${fileCov.lines.hit}/${fileCov.lines.found}`);
          console.log(`Functions Covered: ${fileCov.functions.hit}/${fileCov.functions.found}`);
      });
  });

Using Filters

You can apply filters to focus on specific parts of your codebase. Here’s an example:

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

  fs.readFile('path/to/your/lcov.info', 'utf8', (err, data) => {
      if (err) throw err;
      lcovParse(data, (parseErr, parsedData) => {
          if (parseErr) throw parseErr;

          const filteredData = parsedData.filter(fileCov => fileCov.file.includes('src/'));
          console.log(filteredData);
      });
  });

App Example Using lcov-parse

Let’s build a simple Node.js application that reads an LCOV file, parses it, filters data related to the src directory, and prints a summary:

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

  const app = express();
  const PORT = process.env.PORT || 3000;

  app.get('/coverage', (req, res) => {
      fs.readFile('path/to/your/lcov.info', 'utf8', (err, data) => {
          if (err) return res.status(500).send('Error reading LCOV file');
          lcovParse(data, (parseErr, parsedData) => {
              if (parseErr) return res.status(500).send('Error parsing LCOV data');

              const filteredData = parsedData.filter(fileCov => fileCov.file.includes('src/'));
              res.json(filteredData);
          });
      });
  });

  app.listen(PORT, () => {
      console.log(`Server running on port ${PORT}`);
  });

This application sets up an Express server with a single endpoint /coverage that reads the LCOV file, parses it, applies a filter to focus on files within the src directory, and returns the filtered coverage data as a JSON response.

With these basic examples, you can start leveraging lcov-parse to enhance your code coverage analysis and reporting.

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