Refactor exports-last

CHANGELOG.md

@@ -7,6 +7,7 @@ This change log adheres to standards from [Keep a CHANGELOG](http://keepachangel
 ### Added
 - [`no-anonymous-default-export`] rule: report anonymous default exports ([#712], thanks [@duncanbeevers]).
 - Add new value to `order`'s `newlines-between` option to allow newlines inside import groups ([#627], [#628], thanks [@giodamelio])
+- [`exports-last`] lints that export statements are at the end of the file ([#620] + [#632])
 
 ### Changed
 - [`no-extraneous-dependencies`]: use `read-pkg-up` to simplify finding + loading `package.json` ([#680], thanks [@wtgtybhertgeghgtwtg])
@@ -35,9 +36,6 @@ This change log adheres to standards from [Keep a CHANGELOG](http://keepachangel
 - Properly report [`newline-after-import`] when next line is a decorator
 - Fixed documentation for the default values for the [`order`] rule ([#601])
 
-### Added
-- [`exports-last`] lints that export statements are at the end of the file ([#620] + [#632])
-
 ## [2.0.1] - 2016-10-06
 ### Fixed
 - Fixed code that relied on removed dependencies. ([#604])

docs/rules/exports-last.md

@@ -1,6 +1,6 @@
 # exports-last
 
-This rule reports all export declaration which come before any non-export statements.
+This rule enforces that all exports are declared at the bottom of the file. This rule will report any export declarations that comes before any non-export statements.
 
 
 ## This will be reported
@@ -26,6 +26,8 @@ const str = 'foo'
 ## This will not be reported
 
 ```JS
+const arr = ['bar']
+
 export const bool = true
 
 export default bool

src/rules/exports-last.js

@@ -1,17 +1,23 @@
-const isExportStatement = ({ type }) =>
-  type === 'ExportDefaultDeclaration'
-  || type === 'ExportNamedDeclaration'
-  || type === 'ExportAllDeclaration'
+function isNonExportStatement({ type }) {
+  return type !== 'ExportDefaultDeclaration' &&
+    type !== 'ExportNamedDeclaration' &&
+    type !== 'ExportAllDeclaration'
+}
 
-const rule = {
-  create(context) {
+module.exports = {
+  create: function (context) {
     return {
-      Program({ body }) {
-        const firstExportStatementIndex = body.findIndex(isExportStatement)
+      Program: function ({ body }) {
+        const lastNonExportStatementIndex = body.reduce(function findLastIndex(acc, item, index) {
+          if (isNonExportStatement(item)) {
+            return index
+          }
+          return acc
+        }, -1)
 
-        if (firstExportStatementIndex !== -1) {
-          body.slice(firstExportStatementIndex).forEach((node) => {
-            if (!isExportStatement(node)) {
+        if (lastNonExportStatementIndex !== -1) {
+          body.slice(0, lastNonExportStatementIndex).forEach(function checkNonExport(node) {
+            if (!isNonExportStatement(node)) {
               context.report({
                 node,
                 message: 'Export statements should appear at the end of the file',
@@ -23,5 +29,3 @@ const rule = {
     }
   },
 }
-
-export default rule

tests/src/rules/exports-last.js

@@ -5,13 +5,17 @@ import rule from 'rules/exports-last'
 
 const ruleTester = new RuleTester()
 
-const errors = ['Export statements should appear at the end of the file']
+const error = type => ({
+  ruleId: 'exports-last',
+  message: 'Export statements should appear at the end of the file',
+  type
+});
 
 ruleTester.run('exports-last', rule, {
   valid: [
     // Empty file
     test({
-      code: '',
+      code: '// comment',
     }),
     test({
       // No exports
@@ -82,23 +86,23 @@ ruleTester.run('exports-last', rule, {
         export default 'bar'
         const bar = true
       `,
-      errors,
+      errors: [error('ExportDefaultDeclaration')],
     }),
     // Named export before variable declaration
     test({
       code: `
         export const foo = 'bar'
         const bar = true
       `,
-      errors,
+      errors: [error('ExportNamedDeclaration')],
     }),
     // Export all before variable declaration
     test({
       code: `
         export * from './foo'
         const bar = true
       `,
-      errors,
+      errors: [error('ExportAllDeclaration')],
     }),
     // Many exports arround variable declaration
     test({
@@ -111,7 +115,10 @@ ruleTester.run('exports-last', rule, {
         export const even = 'count'
         export const how = 'many'
       `,
-      errors,
+      errors: [
+        error('ExportDefaultDeclaration'),
+        error('ExportNamedDeclaration'),
+      ],
     }),
   ],
 })