Refactor prefer-trim-start-end with selector (#518)

Author: fisker

rules/prefer-trim-start-end.js

@@ -1,43 +1,30 @@
 'use strict';
 const getDocumentationUrl = require('./utils/get-documentation-url');
+const methodSelector = require('./utils/method-selector');
 
+const selector = methodSelector({length: 0});
 const methods = new Map([
 	['trimLeft', 'trimStart'],
 	['trimRight', 'trimEnd']
 ]);
 
 const messages = {};
-
 for (const [method, replacement] of methods.entries()) {
 	messages[method] = `Prefer \`String#${method}()\` over \`String#${replacement}()\`.`;
 }
 
 const create = context => {
 	return {
-		CallExpression(node) {
-			const {callee, arguments: arguments_} = node;
-
-			if (
-				callee.type !== 'MemberExpression' ||
-				callee.property.type !== 'Identifier' ||
-				arguments_.length !== 0
-			) {
-				return;
+		[selector](node) {
+			const {property} = node.callee;
+			const method = property.name;
+			if (methods.has(method)) {
+				context.report({
+					node,
+					messageId: method,
+					fix: fixer => fixer.replaceText(property, methods.get(method))
+				});
 			}
-
-			const method = callee.property.name;
-
-			if (!methods.has(method)) {
-				return;
-			}
-
-			const replacement = methods.get(method);
-
-			context.report({
-				node,
-				messageId: method,
-				fix: fixer => fixer.replaceText(callee.property, replacement)
-			});
 		}
 	};
 };

rules/utils/method-selector.js

@@ -11,7 +11,7 @@ module.exports = options => {
 		'[callee.type="MemberExpression"]',
 		'[callee.computed=false]',
 		'[callee.property.type="Identifier"]',
-		`[callee.property.name="${name}"]`,
+		name ? `[callee.property.name="${name}"]` : '',
 		`[arguments.length=${length}]`,
 		...(
 			allowSpreadElement ?

test/prefer-trim-start-end.js

@@ -22,14 +22,19 @@ ruleTester.run('prefer-flat-map', rule, {
 	valid: [
 		'foo.trimStart()',
 		'foo.trimEnd()',
-		// Extra arguments
-		'foo.trimLeft(1)',
-		// New
-		'new foo.trimLeft()',
-		// Function call
-		'trimLeft()',
-		// Not call
-		'foo.trimLeft'
+		// Not `CallExpression`
+		'new foo.trimLeft();',
+		// Not `MemberExpression`
+		'trimLeft();',
+		// `callee.property` is not a `Identifier`
+		'foo[\'trimLeft\']();',
+		// Computed
+		'foo[trimLeft]();',
+		// Not `trimLeft`/`trimRight`
+		'foo.bar();',
+		// More argument(s)
+		'foo.trimLeft(extra);',
+		'foo.trimLeft(...argumentsArray)'
 	],
 	invalid: [
 		{