eslint-plugin-ava/rules/use-true-false.js

ESLint rules for AVA

'use strict';

const {isDeepStrictEqual} = require('node:util');
const espree = require('espree');
const espurify = require('espurify');
const {visitIf} = require('enhance-visitors');
const util = require('../util');
const createAvaRule = require('../create-ava-rule');

const booleanBinaryOperators = new Set([
	'==',
	'===',
	'!=',
	'!==',
	'<',
	'<=',
	'>',
	'>=',
]);

const knownBooleanSignatures = [
	'isFinite()',
	'isNaN()',
	'Object.is()',
	'Object.isExtensible()',
	'Object.isFrozen()',
	'Object.isSealed()',
	'Boolean()',
	'Number.isNaN()',
	'Number.isFinite()',
	'Number.isInteger()',
	'Number.isSafeInteger()',
	'Array.isArray()',
	'ArrayBuffer.isView()',
	'SharedArrayBuffer.isView()',
	'Reflect.has()',
	'Reflect.isExtensible()',
].map(signature => espurify(espree.parse(signature).body[0].expression.callee));

function matchesKnownBooleanExpression(argument) {
	if (argument.type !== 'CallExpression') {
		return false;
	}

	const callee = espurify(argument.callee);

	return knownBooleanSignatures.some(signature => isDeepStrictEqual(callee, signature));
}

const create = context => {
	const ava = createAvaRule();

	return ava.merge({
		CallExpression: visitIf([
			ava.isInTestFile,
			ava.isInTestNode,
		])(node => {
			if (
				node.callee.type === 'MemberExpression'
				&& (node.callee.property.name === 'truthy' || node.callee.property.name === 'falsy')
				&& node.callee.object.name === 't'
			) {
				const argument = node.arguments[0];

				if (argument
					&& ((argument.type === 'BinaryExpression' && booleanBinaryOperators.has(argument.operator))
					|| (argument.type === 'UnaryExpression' && argument.operator === '!')
					|| (argument.type === 'Literal' && argument.value === Boolean(argument.value))
					|| (matchesKnownBooleanExpression(argument)))
				) {
					if (node.callee.property.name === 'falsy') {
						context.report({
							node,
							message: '`t.false()` should be used instead of `t.falsy()`.',
						});
					} else {
						context.report({
							node,
							message: '`t.true()` should be used instead of `t.truthy()`.',
						});
					}
				}
			}
		}),
	});
};

module.exports = {
	create,
	meta: {
		type: 'suggestion',
		docs: {
			description: 'Ensure that `t.true()`/`t.false()` are used instead of `t.truthy()`/`t.falsy()`.',
			url: util.getDocsUrl(__filename),
		},
		schema: [],
	},
};