From f22cb6838caa14e30b33f9115d5626eaf588c484 Mon Sep 17 00:00:00 2001
From: Matthieu Lemoine <ml.94230@gmail.com>
Date: Thu, 17 Aug 2017 06:41:17 +0200
Subject: [PATCH] fix: Fix strip extensions for RN support (#205)

---
 README.md                                | 18 +++++++++++++++
 src/resolvePath.js                       |  1 +
 src/utils.js                             | 17 ++++++++++++--
 test/index.test.js                       | 28 ++++++++++++++++++++++++
 test/testproject/src/rn/index.android.js |  0
 test/testproject/src/rn/index.ios.js     |  0
 6 files changed, 62 insertions(+), 2 deletions(-)
 create mode 100644 test/testproject/src/rn/index.android.js
 create mode 100644 test/testproject/src/rn/index.ios.js

diff --git a/README.md b/README.md
index 11cea6e..a029974 100644
--- a/README.md
+++ b/README.md
@@ -82,6 +82,24 @@ To use the backslash character (`\`) just escape it like so: `'\\\\'` (double es
 
 If you're using ESLint, you should use [eslint-plugin-import][eslint-plugin-import], and [eslint-import-resolver-babel-module][eslint-import-resolver-babel-module] to remove falsy unresolved modules.
 
+## Usage with React Native
+
+To let the packager resolve the right module for each platform, you have to add the ```.ios.js```and ```.android.js``` extensions :
+
+```json
+{
+  "plugins": [
+    [
+      "module-resolver",
+      {
+        "root": ["./src"],
+        "extensions": [".js", ".ios.js", ".android.js"]
+      }
+    ]
+  ]
+}
+```
+
 ## Usage with Flow
 
 To allow Flow to find your modules, add configuration options
diff --git a/src/resolvePath.js b/src/resolvePath.js
index 8ac816d..bb05a76 100644
--- a/src/resolvePath.js
+++ b/src/resolvePath.js
@@ -33,6 +33,7 @@ function resolvePathFromRootConfig(sourcePath, currentFile, opts) {
   return toLocalPath(toPosixPath(replaceExtension(
     mapToRelative(opts.cwd, currentFile, absFileInRoot),
     ext,
+    opts,
   )));
 }
 
diff --git a/src/utils.js b/src/utils.js
index 8dd8907..ceb87a7 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -21,8 +21,21 @@ export function toLocalPath(modulePath) {
     .replace(/^(?!\.)/, './'); // insert `./` to make it a local path
 }
 
-export function replaceExtension(modulePath, ext) {
-  const filename = path.basename(modulePath, path.extname(modulePath)) + ext;
+export function stripExtension(modulePath, extensions) {
+  const [name, ...splits] = path.basename(modulePath).split('.');
+  const fileExtension = `.${splits.join('.')}`;
+  return extensions.reduce((filename, extension) => {
+    // To allow filename to contain a dot
+    if (extension === fileExtension) {
+      // Strip extension
+      return name;
+    }
+    return filename;
+  }, path.basename(modulePath, path.extname(modulePath)));
+}
+
+export function replaceExtension(modulePath, ext, opts) {
+  const filename = stripExtension(modulePath, opts.extensions) + ext;
   return path.join(path.dirname(modulePath), filename);
 }
 
diff --git a/test/index.test.js b/test/index.test.js
index aa6c098..df2d0c4 100644
--- a/test/index.test.js
+++ b/test/index.test.js
@@ -235,6 +235,34 @@ describe('module-resolver', () => {
       });
     });
 
+    describe('non-standard double extensions', () => {
+      const rootTransformerOpts = {
+        babelrc: false,
+        plugins: [
+          [plugin, {
+            root: './test/testproject/src',
+            extensions: ['.js', '.ios.js', '.android.js'],
+          }],
+        ],
+      };
+
+      it('should not resolve the file path with an unknown extension', () => {
+        testWithImport(
+          'text',
+          'text',
+          rootTransformerOpts,
+        );
+      });
+
+      it('should resolve the file path with a known defined extension & strip the extension', () => {
+        testWithImport(
+          'rn',
+          './test/testproject/src/rn',
+          rootTransformerOpts,
+        );
+      });
+    });
+
     describe('root and alias', () => {
       const rootTransformerOpts = {
         babelrc: false,
diff --git a/test/testproject/src/rn/index.android.js b/test/testproject/src/rn/index.android.js
new file mode 100644
index 0000000..e69de29
diff --git a/test/testproject/src/rn/index.ios.js b/test/testproject/src/rn/index.ios.js
new file mode 100644
index 0000000..e69de29