tessl/npm-istanbul-lib-coverage

Data library for istanbul coverage objects providing read-only API with merge and summarize capabilities

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Overview

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Files

Coverage Maps

Name: tessl/npm-istanbul-lib-coverage
Author: tessl

Coverage maps are collections of file coverage objects keyed by file path, providing operations for merging, filtering, and analyzing coverage data across multiple files.

Capabilities

CoverageMap Constructor

Creates a new coverage map from existing coverage data or another coverage map.

/**
 * Creates a CoverageMap instance
 * @param {Object|CoverageMap} [obj] - Coverage map data or existing CoverageMap
 */
constructor(obj)

Usage Examples:

const { createCoverageMap } = require('istanbul-lib-coverage');

// Create empty coverage map
const map = createCoverageMap();

// Create from global coverage variable
const map = createCoverageMap(global.__coverage__);

// Create from existing coverage map
const map = createCoverageMap(existingMap);

Merge Coverage Maps

Merges another coverage map into the current one, combining coverage data for matching files.

/**
 * Merges another coverage map into this one
 * @param {CoverageMap|Object} obj - Coverage map to merge
 */
merge(obj): void

Usage Examples:

const map1 = createCoverageMap(coverage1);
const map2 = createCoverageMap(coverage2);

// Merge map2 into map1
map1.merge(map2);

// Merge raw coverage data
map1.merge(rawCoverageData);

Filter Coverage Map

Filters the coverage map based on file paths using a callback function.

/**
 * Filters coverage map based on callback
 * @param {Function} callback - Returns true if path should be included
 */
filter(callback): void

Usage Examples:

const map = createCoverageMap(globalCoverage);

// Keep only JavaScript files
map.filter(filePath => filePath.endsWith('.js'));

// Exclude test files
map.filter(filePath => !filePath.includes('test'));

// Keep specific directory
map.filter(filePath => filePath.startsWith('/src/'));

Get File List

Returns an array of file paths for which the map has coverage data.

/**
 * Returns array of file paths with coverage
 * @returns {string[]} Array of file paths
 */
files(): string[]

Usage Examples:

const map = createCoverageMap(globalCoverage);
const files = map.files();

console.log(`Coverage available for ${files.length} files:`);
files.forEach(file => console.log(file));

Get File Coverage

Returns the file coverage object for a specified file path.

/**
 * Returns file coverage for specified file
 * @param {string} file - File path
 * @returns {FileCoverage} File coverage object
 * @throws {Error} If file not found in map
 */
fileCoverageFor(file): FileCoverage

Usage Examples:

const map = createCoverageMap(globalCoverage);

try {
  const fileCoverage = map.fileCoverageFor('/src/index.js');
  console.log('Line coverage:', fileCoverage.getLineCoverage());
} catch (error) {
  console.error('File not found:', error.message);
}

Add File Coverage

Adds a file coverage object to the map, merging with existing coverage if the path already exists.

/**
 * Adds file coverage to map, merging if path exists
 * @param {FileCoverage} fc - File coverage object to add
 */
addFileCoverage(fc): void

Usage Examples:

const { createCoverageMap, createFileCoverage } = require('istanbul-lib-coverage');

const map = createCoverageMap();
const fileCoverage = createFileCoverage('/src/utils.js');

// Add new file coverage
map.addFileCoverage(fileCoverage);

// Adding duplicate path will merge coverage
const anotherFileCoverage = createFileCoverage('/src/utils.js');
map.addFileCoverage(anotherFileCoverage); // Merges with existing

Get Coverage Summary

Returns an aggregated coverage summary for all files in the map.

/**
 * Returns coverage summary for all files in map
 * @returns {CoverageSummary} Aggregated coverage summary
 */
getCoverageSummary(): CoverageSummary

Usage Examples:

const map = createCoverageMap(globalCoverage);
const summary = map.getCoverageSummary();

console.log('Overall coverage:');
console.log(`Lines: ${summary.lines.pct}%`);
console.log(`Statements: ${summary.statements.pct}%`);
console.log(`Functions: ${summary.functions.pct}%`);
console.log(`Branches: ${summary.branches.pct}%`);

JSON Serialization

Returns a JSON-serializable representation of the coverage map.

/**
 * Returns JSON-serializable POJO
 * @returns {Object} Raw coverage map data
 */
toJSON(): Object

Usage Examples:

const map = createCoverageMap(globalCoverage);
const jsonData = map.toJSON();

// Save to file
const fs = require('fs');
fs.writeFileSync('coverage.json', JSON.stringify(jsonData, null, 2));

// Send over network
response.json(jsonData);