Add prefer-regexp-test rule (#970)

Co-authored-by: Sindre Sorhus <sindresorhus@gmail.com>

docs/rules/prefer-regexp-test.md

@@ -0,0 +1,21 @@
+# Prefer `RegExp#test()` over `String#match()` and `RegExp#exec()`
+
+When you want to know whether a pattern is found in a string, use [`RegExp#test()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/test) instead of [`String#match()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/match) and [`RegExp#exec()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/exec).
+
+This rule is fixable.
+
+## Fail
+
+```js
+if (string.match(/unicorn/)) {}
+```
+
+```js
+if (/unicorn/.exec(string)) {}
+```
+
+## Pass
+
+```js
+if (/unicorn/.test(string)) {}
+```

index.js

@@ -97,6 +97,7 @@ module.exports = {
 				'unicorn/prefer-optional-catch-binding': 'error',
 				'unicorn/prefer-query-selector': 'error',
 				'unicorn/prefer-reflect-apply': 'error',
+				'unicorn/prefer-regexp-test': 'error',
 				'unicorn/prefer-set-has': 'error',
 				'unicorn/prefer-spread': 'error',
 				// TODO: Enable this by default when targeting Node.js 16.

readme.md

@@ -89,6 +89,7 @@ Configure it in `package.json`.
 			"unicorn/prefer-optional-catch-binding": "error",
 			"unicorn/prefer-query-selector": "error",
 			"unicorn/prefer-reflect-apply": "error",
+			"unicorn/prefer-regexp-test": "error",
 			"unicorn/prefer-set-has": "error",
 			"unicorn/prefer-spread": "error",
 			"unicorn/prefer-string-replace-all": "off",
@@ -162,6 +163,7 @@ Configure it in `package.json`.
 - [prefer-optional-catch-binding](docs/rules/prefer-optional-catch-binding.md) - Prefer omitting the `catch` binding parameter. *(fixable)*
 - [prefer-query-selector](docs/rules/prefer-query-selector.md) - Prefer `.querySelector()` over `.getElementById()`, `.querySelectorAll()` over `.getElementsByClassName()` and `.getElementsByTagName()`. *(partly fixable)*
 - [prefer-reflect-apply](docs/rules/prefer-reflect-apply.md) - Prefer `Reflect.apply()` over `Function#apply()`. *(fixable)*
+- [prefer-regexp-test](docs/rules/prefer-regexp-test.md) - Prefer `RegExp#test()` over `String#match()` and `RegExp#exec()`. *(fixable)*
 - [prefer-set-has](docs/rules/prefer-set-has.md) - Prefer `Set#has()` over `Array#includes()` when checking for existence or non-existence. *(fixable)*
 - [prefer-spread](docs/rules/prefer-spread.md) - Prefer the spread operator over `Array.from()`. *(fixable)*
 - [prefer-string-replace-all](docs/rules/prefer-string-replace-all.md) - Prefer `String#replaceAll()` over regex searches with the global flag. *(fixable)*

rules/prefer-regexp-test.js

@@ -0,0 +1,98 @@
+'use strict';
+const {isParenthesized} = require('eslint-utils');
+const getDocumentationUrl = require('./utils/get-documentation-url');
+const methodSelector = require('./utils/method-selector');
+const {isBooleanNode} = require('./utils/boolean');
+const shouldAddParenthesesToMemberExpressionObject = require('./utils/should-add-parentheses-to-member-expression-object');
+
+const MESSAGE_ID_REGEXP_EXEC = 'regexp-exec';
+const MESSAGE_ID_STRING_MATCH = 'string-match';
+const messages = {
+	[MESSAGE_ID_REGEXP_EXEC]: 'Prefer `.test(…)` over `.exec(…)`.',
+	[MESSAGE_ID_STRING_MATCH]: 'Prefer `RegExp#test(…)` over `String#match(…)`.'
+};
+
+const regExpExecCallSelector = methodSelector({
+	name: 'exec',
+	length: 1
+});
+
+const stringMatchCallSelector = methodSelector({
+	name: 'match',
+	length: 1
+});
+
+const create = context => {
+	const sourceCode = context.getSourceCode();
+
+	return {
+		[regExpExecCallSelector](node) {
+			if (!isBooleanNode(node)) {
+				return;
+			}
+
+			node = node.callee.property;
+			context.report({
+				node,
+				messageId: MESSAGE_ID_REGEXP_EXEC,
+				fix: fixer => fixer.replaceText(node, 'test')
+			});
+		},
+		[stringMatchCallSelector](node) {
+			if (!isBooleanNode(node)) {
+				return;
+			}
+
+			const regexpNode = node.arguments[0];
+
+			if (regexpNode.type === 'Literal' && !regexpNode.regex) {
+				return;
+			}
+
+			const stringNode = node.callee.object;
+
+			context.report({
+				node,
+				messageId: MESSAGE_ID_STRING_MATCH,
+				* fix(fixer) {
+					yield fixer.replaceText(node.callee.property, 'test');
+
+					let stringText = sourceCode.getText(stringNode);
+					if (
+						!isParenthesized(regexpNode, sourceCode) &&
+						// Only `SequenceExpression` need add parentheses
+						stringNode.type === 'SequenceExpression'
+					) {
+						stringText = `(${stringText})`;
+					}
+
+					yield fixer.replaceText(regexpNode, stringText);
+
+					let regexpText = sourceCode.getText(regexpNode);
+					if (
+						!isParenthesized(stringNode, sourceCode) &&
+						shouldAddParenthesesToMemberExpressionObject(regexpNode, sourceCode)
+					) {
+						regexpText = `(${regexpText})`;
+					}
+
+					// The nodes that pass `isBooleanNode` cannot have an ASI problem.
+
+					yield fixer.replaceText(stringNode, regexpText);
+				}
+			});
+		}
+	};
+};
+
+module.exports = {
+	create,
+	meta: {
+		type: 'suggestion',
+		docs: {
+			url: getDocumentationUrl(__filename)
+		},
+		fixable: 'code',
+		messages
+	}
+};

test/prefer-regexp-test.js

@@ -0,0 +1,110 @@
+import {outdent} from 'outdent';
+import {test} from './utils/test';
+
+test({
+	valid: [
+		'const bar = !re.test(foo)',
+		// Not `boolean`
+		'const matches = foo.match(re) || []',
+		'const matches = foo.match(re)',
+		'const matches = re.exec(foo)',
+		'while (foo = re.exec(bar)) {}',
+		'while ((foo = re.exec(bar))) {}',
+
+		// Method not match
+		'if (foo.notMatch(re)) {}',
+		'if (re.notExec(foo)) {}',
+		// Not `CallExpression`
+		'if (foo.match) {}',
+		'if (re.exec) {}',
+		// Computed
+		'if (foo[match](re)) {}',
+		'if (re[exec](foo)) {}',
+		'if (foo["match"](re)) {}',
+		'if (re["exec"](foo)) {}',
+		// Not `MemberExpression`
+		'if (match(re)) {}',
+		'if (exec(foo)) {}',
+		// More/Less arguments
+		'if (foo.match()) {}',
+		'if (re.exec()) {}',
+		'if (foo.match(re, another)) {}',
+		'if (re.exec(foo, another)) {}',
+		'if (foo.match(...[regexp])) {}',
+		'if (re.exec(...[string])) {}',
+		// Not regex
+		'if (foo.match(1)) {}',
+		'if (foo.match("1")) {}',
+		'if (foo.match(null)) {}',
+		'if (foo.match(1n)) {}',
+		'if (foo.match(true)) {}'
+	],
+	invalid: []
+});
+
+test.visualize([
+	// `String#match()`
+	'const bar = !foo.match(re)',
+	'const bar = Boolean(foo.match(re))',
+	'if (foo.match(re)) {}',
+	'const bar = foo.match(re) ? 1 : 2',
+	'while (foo.match(re)) foo = foo.slice(1);',
+	'do {foo = foo.slice(1)} while (foo.match(re));',
+	'for (; foo.match(re); ) foo = foo.slice(1);',
+
+	// `RegExp#exec()`
+	'const bar = !re.exec(foo)',
+	'const bar = Boolean(re.exec(foo))',
+	'if (re.exec(foo)) {}',
+	'const bar = re.exec(foo) ? 1 : 2',
+	'while (re.exec(foo)) foo = foo.slice(1);',
+	'do {foo = foo.slice(1)} while (re.exec(foo));',
+	'for (; re.exec(foo); ) foo = foo.slice(1);',
+
+	// Parentheses
+	'if ((0, foo).match(re)) {}',
+	'if ((0, foo).match((re))) {}',
+	'if ((foo).match(re)) {}',
+	'if ((foo).match((re))) {}',
+	'if (foo.match(/re/)) {}',
+	'if (foo.match(bar)) {}',
+	'if (foo.match(bar.baz)) {}',
+	'if (foo.match(bar.baz())) {}',
+	'if (foo.match(new RegExp("re", "g"))) {}',
+	'if (foo.match(new SomeRegExp())) {}',
+	'if (foo.match(new SomeRegExp)) {}',
+	'if (foo.match(bar?.baz)) {}',
+	'if (foo.match(bar?.baz())) {}',
+	'if (foo.match(bar || baz)) {}',
+	outdent`
+		async function a() {
+			if (foo.match(await bar())) {}
+		}
+	`,
+	'if ((foo).match(/re/)) {}',
+	'if ((foo).match(new SomeRegExp)) {}',
+	'if ((foo).match(bar?.baz)) {}',
+	'if ((foo).match(bar?.baz())) {}',
+	'if ((foo).match(bar || baz)) {}',
+	outdent`
+		async function a() {
+			if ((foo).match(await bar())) {}
+		}
+	`,
+	// Should not need handle ASI problem
+	'if (foo.match([re][0])) {}',
+
+	// Comments
+	outdent`
+		async function a() {
+			if (
+				/* 1 */ foo() /* 2 */
+					./* 3 */ match /* 4 */ (
+						/* 5 */ await /* 6 */ bar() /* 7 */
+						,
+						/* 8 */
+					)
+			) {}
+		}
+	`
+]);