From 94e2b7df85b4a533446fd884822919048ffd4408 Mon Sep 17 00:00:00 2001
From: Martin Goffan <martin.goffan@me.com>
Date: Tue, 27 Dec 2016 11:59:58 -0300
Subject: [PATCH] Added ability to transform constants name

---
 README.md     | 20 ++++++++++++++++++++
 src/index.js  |  7 +++++--
 test/index.js | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 64fd3f9..0eba5c0 100644
--- a/README.md
+++ b/README.md
@@ -58,6 +58,26 @@ module.exports = constants('todos', [
 // }
 ```
 
+#### Transform constants
+You can pass a custom transform function as well:
+```js
+module.exports = constants('todos', [
+    'add todo',
+    'remove todo',
+    'toggle todo'
+], {
+    separator: '/',
+    transform: function (v) {
+        return v.replace(/\ /g, '_').toUpperCase();
+    }
+});
+// {
+//   'ADD_TODO': 'todos/ADD_TODO',
+//   'REMOVE_TODO': 'todos/REMOVE_TODO'
+//   'TOGGLE_TODO': 'todos/TOGGLE_TODO'
+// }
+```
+
 ## License
 
 Copyright (c) 2016 Cheton Wu
diff --git a/src/index.js b/src/index.js
index b8aeb84..c618fb4 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,5 +1,6 @@
 const defaultOptions = {
-    separator: ':'
+    separator: ':',
+    transform: v => v
 };
 
 const constants = (namespace = '', constants = [], options = defaultOptions) => {
@@ -9,12 +10,14 @@ const constants = (namespace = '', constants = [], options = defaultOptions) =>
     }
 
     options.separator = options.separator || defaultOptions.separator;
+    options.transform = options.transform || defaultOptions.transform;
 
     // Prevent new properties from being added to it
     return Object.freeze(constants.reduce((memo, constant) => {
+        const transformedConstant = options.transform(constant)
         return {
             ...memo,
-            [constant]: namespace ? `${namespace}${options.separator}${constant}` : constant
+            [transformedConstant]: namespace ? `${namespace}${options.separator}${transformedConstant}` : transformedConstant
         };
     }, {}));
 };
diff --git a/test/index.js b/test/index.js
index e157f6c..ca424ac 100644
--- a/test/index.js
+++ b/test/index.js
@@ -33,3 +33,38 @@ test('namespace action constants with a custom separator', (t) => {
     t.same(result, wanted);
     t.end();
 });
+
+test('namespace action constants with a custom transform', (t) => {
+    const result = constants('todos', [
+        'add todo',
+        'remove todo',
+        'toggle todo'
+    ], {
+        separator: '/',
+        transform: v => v.replace(/\ /g, '_').toUpperCase()
+    })
+    const wanted = {
+        'ADD_TODO': 'todos/ADD_TODO',
+        'REMOVE_TODO': 'todos/REMOVE_TODO',
+        'TOGGLE_TODO': 'todos/TOGGLE_TODO'
+    };
+    t.same(result, wanted);
+    t.end();
+})
+
+test('namespace action constants with a custom separator and custom transform', (t) => {
+    const result = constants('todos', [
+        'add todo',
+        'remove todo',
+        'toggle todo'
+    ], {
+        transform: v => v.replace(/\ /g, '_').toUpperCase()
+    })
+    const wanted = {
+        'ADD_TODO': 'todos:ADD_TODO',
+        'REMOVE_TODO': 'todos:REMOVE_TODO',
+        'TOGGLE_TODO': 'todos:TOGGLE_TODO'
+    };
+    t.same(result, wanted);
+    t.end();
+})
\ No newline at end of file