Add string-content rule

rules/string-content.js

@@ -0,0 +1,103 @@
+'use strict';
+const getDocumentationUrl = require('./utils/get-documentation-url');
+
+const MAX_REPLACEMENTS = 3;
+
+function message(replacements) {
+	replacements = replacements.map(({match, suggest}) => `\`${suggest}\` over \`${match}\``);
+
+	const last = replacements.pop();
+
+	const hasMore = replacements.length >= MAX_REPLACEMENTS - 1;
+
+	let message = 'Prefer ';
+	if (replacements.length !== 0) {
+		message += replacements.slice(0, MAX_REPLACEMENTS - 1).join(' ,');
+
+		if (hasMore) {
+			message += ' …';
+		}
+
+		message += ' and ';
+	}
+
+	return `${message}${last}`;
+}
+
+const create = context => {
+	const {patterns = []} = context.options[0] || {};
+
+	if (patterns.length === 0) {
+		return {};
+	}
+
+	return {
+		Literal: node => {
+			const {value} = node;
+
+			if (typeof value !== 'string') {
+				return;
+			}
+
+			const reportedPatterns = patterns.filter(({match}) => value.includes(match));
+
+			if (reportedPatterns.length === 0) {
+				return;
+			}
+
+			const fixed = reportedPatterns.filter(({fix}) => fix).reduce((fixed, {match, suggest}) => fixed.split(match).join(suggest), value);
+			const quote = node.raw[0];
+			const escaped = fixed.replace(new RegExp(quote, 'g'), `\\${quote}`);
+			const fix = fixed === value ?
+				undefined :
+				fixer => fixer.replaceTextRange([node.range[0] + 1, node.range[1] - 1], escaped);
+
+			context.report({
+				node,
+				message: message(reportedPatterns),
+				fix
+			});
+		}
+	};
+};
+
+const patternSchema = {
+	type: 'object',
+	properties: {
+		match: {
+			type: 'string',
+			require: true
+		},
+		suggest: {
+			type: 'string',
+			require: true
+		},
+		fix: {
+			type: 'boolean',
+			default: true
+		}
+	},
+	additionalProperties: false
+};
+const schema = [{
+	type: 'object',
+	properties: {
+		patterns: {
+			type: 'array',
+			items: patternSchema
+		}
+	},
+	additionalProperties: false
+}];
+
+module.exports = {
+	create,
+	meta: {
+		type: 'suggestion',
+		docs: {
+			url: getDocumentationUrl(__filename)
+		},
+		fixable: 'code',
+		schema
+	}
+};

test/string-content.js

@@ -0,0 +1,92 @@
+import test from 'ava';
+import avaRuleTester from 'eslint-ava-rule-tester';
+import rule from '../rules/string-content';
+
+const ruleTester = avaRuleTester(test, {
+	env: {
+		es6: true
+	}
+});
+
+const patterns = {
+	unicorn: {
+		match: 'unicorn',
+		suggest: '🦄'
+	},
+	awesome: {
+		match: 'awesome',
+		suggest: '😎'
+	}
+};
+
+function invalidCase({
+	code,
+	message,
+	patterns,
+	output = code
+}) {
+	return {
+		code,
+		output,
+		options: [{patterns}],
+		errors: [{message}]
+	};
+}
+
+ruleTester.run('string-content', rule, {
+	valid: [
+		'const foo = \'🦄\''
+	],
+	invalid: [
+		{
+			code: 'const foo = \'unicorn\'',
+			output: 'const foo = \'🦄\'',
+			message: 'Prefer `🦄` over `unicorn`',
+			patterns: [patterns.unicorn]
+		},
+		// Escape single quote
+		{
+			code: 'const foo = \'_\'',
+			output: 'const foo = \'\\\'"\'',
+			message: 'Prefer `\'"` over `_`',
+			patterns: [{match: '_', suggest: '\'"'}]
+		},
+		// Escape double quote
+		{
+			code: 'const foo = "_"',
+			output: 'const foo = "\'\\""',
+			message: 'Prefer `\'"` over `_`',
+			patterns: [{match: '_', suggest: '\'"'}]
+		},
+		// Not fix
+		{
+			code: 'const foo = \'unicorn\'',
+			message: 'Prefer `🦄` over `unicorn`',
+			patterns: [{...patterns.unicorn, fix: false}]
+		},
+		// Multi patterns
+		{
+			code: 'const foo = \'unicorn is awesome\'',
+			output: 'const foo = \'🦄 is 😎\'',
+			message: 'Prefer `🦄` over `unicorn` and `😎` over `awesome`',
+			patterns: [patterns.unicorn, patterns.awesome]
+		},
+		// Multi patterns, Not fix `awesome`
+		{
+			code: 'const foo = \'unicorn is awesome\'',
+			output: 'const foo = \'🦄 is awesome\'',
+			message: 'Prefer `🦄` over `unicorn` and `😎` over `awesome`',
+			patterns: [patterns.unicorn, {...patterns.awesome, fix: false}]
+		},
+		// Many patterns
+		{
+			code: 'const foo = \'abcdefghijklmnopqrstuvwxyz\'',
+			output: 'const foo = \'ABCDEFGHIJKLMNOPQRSTUVWXYZ\'',
+			message: 'Prefer `A` over `a` ,`B` over `b` … and `Z` over `z`',
+			patterns: Array.from({length: 26}, (_, index) => ({
+				match: String.fromCharCode('a'.charCodeAt(0) + index),
+				suggest: String.fromCharCode('A'.charCodeAt(0) + index)
+			}))
+		}
+	].map(invalidCase)
+});