A command-line interface for running ESLint rule unit tests powered by the official RuleTester API.

Running the test

npm install eslint-rule-tester

npm exec eslint-rule-tester -- [--bail] [--silent] [<...path>]

Where <...path> is zero or more Glob patterns pointing to rule-name.test.js files that look like the below.

import { test } from 'eslint-rule-tester'

// See https://eslint.org/docs/latest/extend/plugins#creating-a-plugin
const plugin = {
	rules: {
		// ⚠️ The rule name should match the file name or else the tester will use the one rule specified here.
		'rule-name': {
			create(context) {
				// Your rule goes here
			}
		}
	}
}

// See https://eslint.org/docs/latest/extend/custom-rules#rule-structure
const tests = {
	valid: [],
	invalid: []
}

// This represents the base configurations for the tests above.
const options = {
	// The below is the default.
	languageOptions: {
		ecmaVersion: 'latest',
		sourceType: 'module',
	}
}

// The `test` function wraps the arguments into an object and provides type checking only.
export default test(plugin, tests, options)

The command returns the status code representing the number of non-passing test results.

Running selective test cases

To run fewer test cases for debugging purposes, choose one of the following approaches:

• Manually set only: true in your test case as mentioned in ESLint official documentation, for example,

  const tests = {
  	valid: [
  		{
  			code: '...',
  			only: true
  		}
  	],
  	invalid: [...]
  }

• Wrap your test case(s) with the function only imported from this package, for example,

  import { only } from 'eslint-rule-tester'
  
  const tests = {
  	valid: [
  		only({
  			code: '...'
  		})
  	],
  	invalid: only([...]) // This works too.
  }

Sample command-line output

⚪ import-path-from-closest-index
🟢 react-sort-props
🔴 require-name-after-file-name

 1 var something = require("./james-arthur")
	 filename: ./rules/require-name-after-file-name.js
	 options: [
		 [
			 "./rules/*.js"
		 ]
	 ]
	 Should have 1 error but had 0: [] (0 strictEqual 1)

 SKIP  1
 PASS  1
 FAIL  1