feat(extensions): implement import path replacement for consistent file extensions

Author: stephenjason89

src/rules/extensions.js

@@ -183,6 +183,13 @@ module.exports = {
       }
     }
 
+    function replaceImportPath(source, importPath) {
+      return source.replace(
+        /^(['"])(.+)\1$/,
+        (_, quote) => `${quote}${importPath}${quote}`,
+      )
+    }
+
     function checkFileExtension(source, node) {
       // bail if the declaration doesn't have a source, e.g. "export { foo };", or if it's only partially typed like in an editor
       if (!source || !source.value) { return; }
@@ -227,6 +234,19 @@ module.exports = {
         const extensionRequired = isUseOfExtensionRequired(extension, !overrideAction && isPackage);
         const extensionForbidden = isUseOfExtensionForbidden(extension);
         if (extensionRequired && !extensionForbidden) {
+          const fixedImportPath = stringifyPath({
+              pathname: `${
+                /([\\/]|[\\/]?\.?\.)$/.test(importPath)
+                  ? `${
+                      importPath.endsWith('/')
+                        ? importPath.slice(0, -1)
+                        : importPath
+                    }/index.${extension}`
+                  : `${importPath}.${extension}`
+              }`,
+              query,
+              hash,
+            })
           context.report({
             node: source,
             message:
@@ -235,7 +255,7 @@ module.exports = {
               fix(fixer) {
                 return fixer.replaceText(
                   source,
-                  JSON.stringify(`${importPathWithQueryString}.${extension}`),
+                  replaceImportPath(source.raw, fixedImportPath),
                 );
               },
             } : {},