feat(extensions): add autofix support for consistent file extensions in import paths

Author: stephenjason89

README.md

@@ -76,7 +76,7 @@ This plugin intends to support linting of ES2015+ (ES6+) import/export syntax, a
 | [consistent-type-specifier-style](docs/rules/consistent-type-specifier-style.md) | Enforce or ban the use of inline type-only markers for named imports.      |    |       |    | 🔧 |    |    |
 | [dynamic-import-chunkname](docs/rules/dynamic-import-chunkname.md)               | Enforce a leading comment with the webpackChunkName for dynamic imports.   |    |       |    |    | 💡 |    |
 | [exports-last](docs/rules/exports-last.md)                                       | Ensure all exports appear after other statements.                          |    |       |    |    |    |    |
-| [extensions](docs/rules/extensions.md)                                           | Ensure consistent use of file extension within the import path.            |    |       |    |    |    |    |
+| [extensions](docs/rules/extensions.md)                                           | Ensure consistent use of file extension within the import path.            |    |       |    | 🔧 |    |    |
 | [first](docs/rules/first.md)                                                     | Ensure all imports appear before other statements.                         |    |       |    | 🔧 |    |    |
 | [group-exports](docs/rules/group-exports.md)                                     | Prefer named exports to be grouped together in a single export declaration |    |       |    |    |    |    |
 | [imports-first](docs/rules/imports-first.md)                                     | Replaced by `import/first`.                                                |    |       |    | 🔧 |    | ❌  |

docs/rules/extensions.md

@@ -1,5 +1,7 @@
 # import/extensions
 
+🔧 This rule is automatically fixable by the [`--fix` CLI option](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix).
+
 <!-- end auto-generated rule header -->
 
 Some file resolve algorithms allow you to omit the file extension within the import source path. For example the `node` resolver (which does not yet support ESM/`import`) can resolve `./foo/bar` to the absolute path `/User/someone/foo/bar.js` because the `.js` extension is resolved automatically by default in CJS. Depending on the resolver you can configure more extensions to get resolved automatically.

src/rules/extensions.js

@@ -46,6 +46,7 @@ function buildProperties(context) {
     defaultConfig: 'never',
     pattern: {},
     ignorePackages: false,
+    fix: false,
   };
 
   context.options.forEach((obj) => {
@@ -72,6 +73,11 @@ function buildProperties(context) {
       result.ignorePackages = obj.ignorePackages;
     }
 
+    // If fix is provided, transfer it to result
+    if (obj.fix !== undefined) {
+      result.fix = obj.fix;
+    }
+
     if (obj.checkTypeImports !== undefined) {
       result.checkTypeImports = obj.checkTypeImports;
     }
@@ -97,7 +103,7 @@ module.exports = {
       description: 'Ensure consistent use of file extension within the import path.',
       url: docsUrl('extensions'),
     },
-
+    fixable: 'code',
     schema: {
       anyOf: [
         {
@@ -225,13 +231,33 @@ module.exports = {
             node: source,
             message:
               `Missing file extension ${extension ? `"${extension}" ` : ''}for "${importPathWithQueryString}"`,
+            ...props.fix ? {
+              fix(fixer) {
+                if (!extension) { return fixer; }
+                return fixer.replaceText(
+                  source,
+                  JSON.stringify(`${importPathWithQueryString}.${extension}`),
+                );
+              },
+            } : {},
           });
         }
       } else if (extension) {
         if (isUseOfExtensionForbidden(extension) && isResolvableWithoutExtension(importPath)) {
           context.report({
             node: source,
             message: `Unexpected use of file extension "${extension}" for "${importPathWithQueryString}"`,
+            ...props.fix
+              ? {
+                fix(fixer) {
+                  return fixer.replaceText(
+                    source,
+                    JSON.stringify(
+                      importPath.slice(0, -(extension.length + 1)),
+                    ),
+                  );
+                },
+              } : {},
           });
         }
       }