Add no-unreadable-array-destructuring rule

docs/rules/no-unreadable-array-destructuring.md

@@ -0,0 +1,20 @@
+# Disallow unreadable array destructuring
+
+Destructuring is very useful, but it can also make some code harder to read.
+
+## Fail
+
+```js
+const [,, foo] = parts;
+const [,,, foo] = parts;
+const [,,,, foo] = parts;
+```
+
+
+## Pass
+
+```js
+const [, foo] = parts;
+const [foo] = parts;
+const foo = parts[3];
+```

index.js

@@ -22,6 +22,7 @@ module.exports = {
 				'unicorn/filename-case': ['error', {case: 'kebabCase'}],
 				'unicorn/no-abusive-eslint-disable': 'error',
 				'unicorn/no-process-exit': 'error',
+				'unicorn/no-unreadable-array-destructuring': 'error',
 				'unicorn/throw-new-error': 'error',
 				'unicorn/number-literal-case': 'error',
 				'unicorn/escape-case': 'error',

rules/no-unreadable-array-destructuring.js

@@ -0,0 +1,35 @@
+'use strict';
+const getDocsUrl = require('./utils/get-docs-url');
+
+const isCommaFollwedWithComma = (el, index, array) => {
+	if (el === null) {
+		return array[index + 1] === el;
+	}
+};
+
+const create = context => {
+	return {
+		ArrayPattern(node) {
+			const {elements} = node;
+			if (!elements || elements.length === 0) {
+				return;
+			}
+
+			if (elements.some(isCommaFollwedWithComma)) {
+				context.report({
+					node,
+					message: 'Only one ignored value in series allowed in array destructuring.'
+				});
+			}
+		}
+	};
+};
+
+module.exports = {
+	create,
+	meta: {
+		docs: {
+			url: getDocsUrl(__filename)
+		}
+	}
+};

test/no-unreadable-array-destructuring.js

@@ -0,0 +1,39 @@
+import test from 'ava';
+import avaRuleTester from 'eslint-ava-rule-tester';
+import rule from '../rules/no-unreadable-array-destructuring';
+
+const ruleTester = avaRuleTester(test, {
+	env: {
+		es6: true
+	}
+});
+
+ruleTester.run('no-unreadable-array-destructuring', rule, {
+	valid: [
+		'const [, foo] = parts;',
+		'const [foo] = parts;',
+		'const [foo,,bar] = parts;',
+		'const [foo,   ,     bar] = parts;',
+		'const [foo,] = parts;',
+		'const [foo,,] = parts;',
+		'const [foo,, bar,, baz] = parts;'
+	],
+	invalid: [
+		{
+			code: 'const [,, foo] = parts;',
+			errors: [{message: 'Only one ignored value in series allowed in array destructuring.'}]
+		},
+		{
+			code: 'const [foo,,, bar] = parts;',
+			errors: [{message: 'Only one ignored value in series allowed in array destructuring.'}]
+		},
+		{
+			code: 'const [foo,,,] = parts;',
+			errors: [{message: 'Only one ignored value in series allowed in array destructuring.'}]
+		},
+		{
+			code: 'const [foo, bar,, baz ,,, qux] = parts;',
+			errors: [{message: 'Only one ignored value in series allowed in array destructuring.'}]
+		}
+	]
+});