coverage-node

A simple CLI to run Node.js and report code coverage.

• ✨ Zero config.
• 🏁 ~323 SLOC, written from scratch to use code coverage features built into Node.js v10+.
• 📦 ~337 kB install size, compared to 2.2 MB for c8 v7.3.5 or 8.84 MB for nyc v15.1.0.
• 🖱Displays ignored or uncovered source code ranges as paths, clickable in IDEs such as VS Code.

Setup

To install from npm run:

npm install coverage-node --save-dev

In a package.json script, replace the node command with coverage-node:

 {
   "scripts": {
-    "test": "node test.js"
+    "test": "coverage-node test.js"
   }
 }

Support

• Linux, macOS.
• Node.js ^10.17.0 || ^12.0.0 || >= 13.7.0, but for Node.js versions < v13.3 that produce unreliable coverage data the coverage-node CLI skips code coverage and logs a warning.

Ignored files

Code coverage analysis ignores:

• node_modules directory files, e.g. node_modules/foo/index.js.
• test directory files, e.g. test/index.js.
• Files with .test prefixed before the extension, e.g. foo.test.js.
• Files named test (regardless of extension), e.g. test.js.

Ignored lines

In source code, a comment (case insensitive) can be used to ignore code coverage ranges that start on the the next line:

// coverage ignore next line
if (false) console.log('Never runs.');

CLI

The coverage-node command substitutes the normal node command; any node CLI options can be used to run a test script.

If the script doesn’t error a code coverage analysis is reported to the console, and if coverage is incomplete the exit code is 1.

npx can be used to quickly check code coverage for a script:

npx coverage-node test.js

API

Table of contents

• function analyseCoverage
• function reportCoverage
• constant coverageSupported
• constant coverageSupportedMinNodeVersion
• type CoverageAnalysis
• type SemanticVersion
• type SourceCodeLocation
• type SourceCodeRange
• type SourceCodeRanges

function analyseCoverage

Analyzes Node.js generated V8 JavaScript code coverage data in a directory; useful for reporting.

Returns: Promise<CoverageAnalysis> — Resolves the coverage analysis.

Examples

Ways to import.

import { analyseCoverage } from 'coverage-node';

import analyseCoverage from 'coverage-node/public/analyseCoverage.js';

Ways to require.

const { analyseCoverage } = require('coverage-node');

const analyseCoverage = require('coverage-node/public/analyseCoverage');

function reportCoverage

Reports a code coverage analysis to the console.

Examples

Ways to import.

import { reportCoverage } from 'coverage-node';

import reportCoverage from 'coverage-node/public/reportCoverage.js';

Ways to require.

const { reportCoverage } = require('coverage-node');

const reportCoverage = require('coverage-node/public/reportCoverage');

constant coverageSupported

Is the process Node.js version greater at least the minimum required to support code coverage.

Type: boolean

Examples

Ways to import.

import { coverageSupported } from 'coverage-node';

import coverageSupported from 'coverage-node/public/coverageSupported.js';

Ways to require.

const { coverageSupported } = require('coverage-node');

const coverageSupported = require('coverage-node/public/coverageSupported');

constant coverageSupportedMinNodeVersion

Minimum Node.js version supported for code coverage. Although Node.js v10+ supports coverage, only v13.3+ produces coverage data reliable enough to use.

Type: SemanticVersion

Examples

Ways to import.

import { coverageSupportedMinNodeVersion } from 'coverage-node';

import coverageSupportedMinNodeVersion from 'coverage-node/public/coverageSupportedMinNodeVersion.js';

Ways to require.

const { coverageSupportedMinNodeVersion } = require('coverage-node');

const coverageSupportedMinNodeVersion = require('coverage-node/public/coverageSupportedMinNodeVersion');

type CoverageAnalysis

Node.js generated V8 JavaScript code coverage data analysis; useful for reporting.

Type: object

type SemanticVersion

A semantic version.

Type: object

type SourceCodeLocation

Source code location.

Type: object

type SourceCodeRange

Source code range details.

Type: object

type SourceCodeRanges

A source code file with ranges of interest.

Type: object