Add no-console-spaces rule (#191)

docs/rules/no-console-spaces.md

@@ -0,0 +1,38 @@
+# Do not use leading/trailing space between `console.log` parameters
+
+The [`console.log()` method](https://developer.mozilla.org/en-US/docs/Web/API/Console/log) and similar methods joins the parameters with a space, so adding a leading/trailing space to a parameter, results in two spaces being added.
+
+
+## Fail
+
+```js
+console.log('abc ', 'def');
+console.log('abc', ' def');
+
+console.log("abc ", " def");
+console.log(`abc `, ` def`);
+
+console.debug('abc ', 'def');
+console.info('abc ', 'def');
+console.warn('abc ', 'def');
+console.error('abc ', 'def');
+```
+
+
+## Pass
+
+```js
+console.log('abc');
+console.log('abc', 'def');
+
+console.log('abc ');
+console.log(' abc');
+
+console.log('abc  ', 'def');
+console.log('abc\t', 'def');
+console.log('abc\n', 'def');
+
+console.log(`
+	abc
+`);
+```

index.js

@@ -39,7 +39,8 @@ module.exports = {
 				'unicorn/error-message': 'error',
 				'unicorn/no-unsafe-regex': 'off',
 				'unicorn/prefer-add-event-listener': 'error',
-				'unicorn/prefer-exponentiation-operator': 'error'
+				'unicorn/prefer-exponentiation-operator': 'error',
+				'unicorn/no-console-spaces': 'error'
 			}
 		}
 	}

readme.md

@@ -54,7 +54,8 @@ Configure it in `package.json`.
 			"unicorn/prefer-spread": "error",
 			"unicorn/error-message": "error",
 			"unicorn/no-unsafe-regex": "off",
-			"unicorn/prefer-add-event-listener": "error"
+			"unicorn/prefer-add-event-listener": "error",
+			"unicorn/no-console-spaces": "error"
 		}
 	}
 }
@@ -86,6 +87,7 @@ Configure it in `package.json`.
 - [no-unsafe-regex](docs/rules/no-unsafe-regex.md) - Disallow unsafe regular expressions.
 - [prefer-add-event-listener](docs/rules/prefer-add-event-listener.md) - Prefer `addEventListener` over `on`-functions. *(fixable)*
  - [prefer-exponentiation-operator](docs/rules/prefer-exponentiation-operator.md) - Prefer the exponentiation operator over `Math.pow()` *(fixable)*
+ - [no-console-spaces](docs/rules/no-console-spaces.md) - Do not use leading/trailing space between `console.log` parameters. *(fixable)*
 
 
 ## Recommended config

rules/no-console-spaces.js

@@ -0,0 +1,141 @@
+'use strict';
+const getDocsUrl = require('./utils/get-docs-url');
+
+const getConsoleMethod = node => {
+	const methods = [
+		'log',
+		'debug',
+		'info',
+		'warn',
+		'error'
+	];
+
+	const {callee} = node;
+
+	if (
+		callee.type === 'MemberExpression' &&
+		callee.object.type === 'Identifier' &&
+		callee.object.name === 'console' &&
+		callee.property.type === 'Identifier' &&
+		methods.includes(callee.property.name)
+	) {
+		return callee.property.name;
+	}
+};
+
+const getArgumentValue = (context, nodeArgument) => {
+	let value = null;
+
+	if (nodeArgument.type === 'Literal' && typeof nodeArgument.value === 'string') {
+		value = nodeArgument.value;
+	}
+
+	if (nodeArgument.type === 'TemplateLiteral') {
+		const sourceCode = context.getSourceCode();
+		value = sourceCode.getText(nodeArgument);
+		// Strip off backticks
+		value = value.substring(1, value.length - 1);
+	}
+
+	return value;
+};
+
+const fixValue = (value, {
+	fixLeading = true,
+	fixTrailing = true
+}) => {
+	if (!value) {
+		return value;
+	}
+
+	// Allow exactly one space
+	if (value.length <= 1) {
+		return value;
+	}
+
+	let fixed = value;
+
+	// Find exactly one leading space
+	if (fixLeading && fixed.startsWith(' ') && !fixed.startsWith('  ')) {
+		fixed = fixed.slice(1);
+	}
+
+	// Find exactly one trailing space
+	if (fixTrailing && fixed.endsWith(' ') && !fixed.endsWith('  ')) {
+		fixed = fixed.slice(0, -1);
+	}
+
+	return fixed;
+};
+
+const getFixableArguments = (context, node) => {
+	const {
+		arguments: args
+	} = node;
+
+	const fixables = args.map((nodeArgument, i) => {
+		const fixLeading = i !== 0;
+		const fixTrailing = i !== (args.length - 1);
+
+		const value = getArgumentValue(context, nodeArgument);
+		const fixed = fixValue(value, {fixLeading, fixTrailing});
+
+		return {
+			nodeArgument,
+			value,
+			fixed,
+			fixable: value !== fixed
+		};
+	});
+
+	return fixables.filter(fixable => fixable.fixable);
+};
+
+const fixArg = (context, fixable, fixer) => {
+	const {
+		nodeArgument,
+		fixed
+	} = fixable;
+
+	// Ignore quotes and backticks
+	const range = [
+		nodeArgument.range[0] + 1,
+		nodeArgument.range[1] - 1
+	];
+
+	return fixer.replaceTextRange(range, fixed);
+};
+
+const buildErrorMessage = method => {
+	return `Do not use leading/trailing space between \`console.${method}\` parameters.`;
+};
+
+const create = context => {
+	return {
+		CallExpression(node) {
+			const method = getConsoleMethod(node);
+			if (!method) {
+				return;
+			}
+
+			const fixables = getFixableArguments(context, node);
+			for (const fixable of fixables) {
+				context.report({
+					node: fixable.nodeArgument,
+					message: buildErrorMessage(method),
+					fix: fixer => fixArg(context, fixable, fixer)
+				});
+			}
+		}
+	};
+};
+
+module.exports = {
+	create,
+	meta: {
+		docs: {
+			url: getDocsUrl(__filename)
+		},
+		fixable: 'code'
+	}
+};

test/no-console-spaces.js

@@ -0,0 +1,141 @@
+import test from 'ava';
+import avaRuleTester from 'eslint-ava-rule-tester';
+import rule from '../rules/no-console-spaces';
+
+const ruleTester = avaRuleTester(test, {
+	parserOptions: {
+		ecmaVersion: 2016
+	}
+});
+
+function buildError({method, column, line}) {
+	const error = {
+		ruleId: 'no-console-spaces',
+		message: `Do not use leading/trailing space between \`console.${method}\` parameters.`
+	};
+
+	if (column) {
+		error.column = column;
+	}
+
+	if (line) {
+		error.line = line;
+	}
+
+	return error;
+}
+
+ruleTester.run('no-console-spaces', rule, {
+	valid: [
+		'console.log("abc");',
+		'console.log("abc", "def");',
+		'console.log(\'abc\', "def");',
+		'console.log(`abc`, "def");',
+		'console.log("abc", "def");',
+		'console.log(`\nabc\ndef\n`);',
+
+		'console.log(\' \', "def");',
+		'console.log(\'  \', "def");',
+		'console.log("abc  ", "def");',
+		'console.log("abc\\t", "def");',
+		'console.log("abc\\n", "def");',
+		'console.log("  abc", "def");',
+
+		'console.log(" abc", "def");',
+		'console.log("abc", "def ");',
+
+		'console.log();',
+		'console.log("");',
+		'console.log(123);',
+		'console.log(null);',
+		'console.log(undefined);',
+
+		'console.dir("abc ");'
+	],
+	invalid: [
+		{
+			code: 'console.log("abc ", "def");',
+			errors: [buildError({method: 'log'})],
+			output: 'console.log("abc", "def");'
+		},
+		{
+			code: 'console.log("abc", " def");',
+			errors: [buildError({method: 'log'})],
+			output: 'console.log("abc", "def");'
+		},
+		{
+			code: 'console.log(" abc ", "def");',
+			errors: [buildError({method: 'log'})],
+			output: 'console.log(" abc", "def");'
+		},
+		{
+			code: 'console.debug("abc ", "def");',
+			errors: [buildError({method: 'debug'})],
+			output: 'console.debug("abc", "def");'
+		},
+		{
+			code: 'console.info("abc ", "def");',
+			errors: [buildError({method: 'info'})],
+			output: 'console.info("abc", "def");'
+		},
+		{
+			code: 'console.warn("abc ", "def");',
+			errors: [buildError({method: 'warn'})],
+			output: 'console.warn("abc", "def");'
+		},
+		{
+			code: 'console.error("abc ", "def");',
+			errors: [buildError({method: 'error'})],
+			output: 'console.error("abc", "def");'
+		},
+		{
+			code: 'console.log("abc", " def ", "ghi");',
+			errors: [buildError({method: 'log'})],
+			output: 'console.log("abc", "def", "ghi");'
+		},
+		{
+			code: 'console.log("abc ", "def ", "ghi");',
+			errors: [
+				buildError({method: 'log', column: 13}),
+				buildError({method: 'log', column: 21})
+			],
+			output: 'console.log("abc", "def", "ghi");'
+		},
+		{
+			code: 'console.log(\'abc \', "def");',
+			errors: [buildError({method: 'log'})],
+			output: 'console.log(\'abc\', "def");'
+		},
+		{
+			code: 'console.log(`abc `, "def");',
+			errors: [buildError({method: 'log'})],
+			output: 'console.log(`abc`, "def");'
+		},
+		{
+			// eslint-disable-next-line no-template-curly-in-string
+			code: 'console.log(`abc ${1 + 2} `, "def");',
+			errors: [buildError({method: 'log'})],
+			// eslint-disable-next-line no-template-curly-in-string
+			output: 'console.log(`abc ${1 + 2}`, "def");'
+		},
+		{
+			code: `
+				console.log(
+					'abc',
+					'def ',
+					'ghi'
+				);
+			`,
+			errors: [
+				buildError({method: 'log', column: 6, line: 4})
+			],
+			output: `
+				console.log(
+					'abc',
+					'def',
+					'ghi'
+				);
+			`
+		}
+	]
+});