custom-error-definition: Cover exports name (#313)

Author: MrHen

rules/custom-error-definition.js

@@ -2,6 +2,8 @@
 const upperfirst = require('lodash.upperfirst');
 const getDocsUrl = require('./utils/get-docs-url');
 
+const MESSAGE_ID_INVALID_EXPORT = 'invalidExport';
+
 const nameRegexp = /^(?:[A-Z][a-z\d]*)*Error$/;
 
 const getClassName = name => upperfirst(name).replace(/(error|)$/i, 'Error');
@@ -124,10 +126,50 @@ const customErrorDefinition = (context, node) => {
 	}
 };
 
+const customErrorExport = (context, node) => {
+	if (!node.left.object || node.left.object.name !== 'exports') {
+		return;
+	}
+
+	if (!node.left.property) {
+		return;
+	}
+
+	const exportsName = node.left.property.name;
+
+	const maybeError = node.right;
+
+	if (maybeError.type !== 'ClassExpression') {
+		return;
+	}
+
+	if (!hasValidSuperClass(maybeError)) {
+		return;
+	}
+
+	if (!maybeError.id) {
+		return;
+	}
+
+	// Assume rule has already fixed the error name
+	const errorName = maybeError.id.name;
+
+	if (exportsName === errorName) {
+		return;
+	}
+
+	context.report({
+		node: node.left.property,
+		messageId: MESSAGE_ID_INVALID_EXPORT,
+		fix: fixer => fixer.replaceText(node.left.property, errorName)
+	});
+};
+
 const create = context => {
 	return {
 		ClassDeclaration: node => customErrorDefinition(context, node),
-		'AssignmentExpression[right.type="ClassExpression"]': node => customErrorDefinition(context, node.right)
+		'AssignmentExpression[right.type="ClassExpression"]': node => customErrorDefinition(context, node.right),
+		'AssignmentExpression[left.type="MemberExpression"]': node => customErrorExport(context, node)
 	};
 };
 
@@ -138,6 +180,9 @@ module.exports = {
 		docs: {
 			url: getDocsUrl(__filename)
 		},
-		fixable: 'code'
+		fixable: 'code',
+		messages: {
+			[MESSAGE_ID_INVALID_EXPORT]: 'Exported error name should match error class'
+		}
 	}
 };

test/custom-error-definition.js

@@ -17,6 +17,10 @@ const noSuperCallError = {ruleId: 'custom-error-definition', message: 'Missing c
 const invalidNameError = name => ({ruleId: 'custom-error-definition', message: `The \`name\` property should be set to \`${name}\`.`});
 const passMessageToSuperError = {ruleId: 'custom-error-definition', message: 'Pass the error message to `super()`.'};
 const invalidMessageAssignmentError = {ruleId: 'custom-error-definition', message: 'Pass the error message to `super()` instead of setting `this.message`.'};
+const invalidExportError = {
+	ruleId: 'custom-error-definition',
+	messageId: 'invalidExport'
+};
 
 ruleTester.run('custom-error-definition', rule, {
 	valid: [
@@ -110,6 +114,18 @@ ruleTester.run('custom-error-definition', rule, {
 					this.name = 'fooError';
 				}
 			};
+		`,
+		`
+			exports.whatever = class Whatever {};
+		`,
+		`
+			class FooError extends Error {
+				constructor(error) {
+					super(error);
+					this.name = 'FooError';
+				}
+			};
+			exports.fooError = FooError;
 		`
 	],
 	invalid: [
@@ -356,20 +372,25 @@ ruleTester.run('custom-error-definition', rule, {
 				invalidNameError('FooError')
 			]
 		},
-		// TODO: Uncomment test as part of #190
-		// {
-		// 	code: `
-		// 		exports.fooError = class FooError extends Error {
-		// 			constructor(error) {
-		// 				super(error);
-		// 				this.name = 'FooError';
-		// 			}
-		// 		};
-		// 	`,
-		// 	errors: [
-		// 		invalidNameError('fooError')
-		// 	]
-		// },
+		{
+			code: `
+				exports.fooError = class FooError extends Error {
+					constructor(error) {
+						super(error);
+						this.name = 'FooError';
+					}
+				};
+			`,
+			errors: [invalidExportError],
+			output: `
+				exports.FooError = class FooError extends Error {
+					constructor(error) {
+						super(error);
+						this.name = 'FooError';
+					}
+				};
+			`
+		},
 		{
 			code: `
 				exports.FooError = class FooError extends TypeError {