coverage-node

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

• ✨ Zero config.
• 🏁 Tiny source, written from scratch to use code coverage features built into Node.js.
• 📦 Lean install size, compared to 1.94 MB for c8 v7.11.1 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.

Installation

To install coverage-node with npm, run:

npm install coverage-node --save-dev

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

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

Requirements

Supported operating systems:

• Linux
• macOS

Supported runtime environments:

• Node.js versions ^14.17.0 || ^16.0.0 || >= 18.0.0.

Projects must configure TypeScript to use types from the ECMAScript modules that have a // @ts-check comment:

• compilerOptions.allowJs should be true.
• compilerOptions.maxNodeModuleJsDepth should be reasonably large, e.g. 10.
• compilerOptions.module should be "node16" or "nodenext".

Ignored files

Code coverage analysis ignores:

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

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

Command coverage-node

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 and there isn’t a truthy ALLOW_MISSING_COVERAGE environment variable the process exits with code 1.

Examples

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

npx coverage-node test.mjs

A package.json script:

{
  "scripts": {
    "test": "coverage-node test.mjs"
  }
}

A package.json script that allows missing coverage:

{
  "scripts": {
    "test": "ALLOW_MISSING_COVERAGE=1 coverage-node test.mjs"
  }
}

Exports

The npm package coverage-node features optimal JavaScript module design. It doesn’t have a main index module, so use deep imports from the ECMAScript modules that are exported via the package.json field exports:

• analyseCoverage.mjs
• reportCoverage.mjs