Enable mocking of const

.travis.yml

@@ -4,6 +4,7 @@ node_js:
   - "0.12"
   - "4"
   - "5"
+  - "6"
 
 script:
   - npm test

README.md

@@ -139,9 +139,6 @@ myModule.__with__({
 Limitations
 -----------
 
-**Using `const`**<br>
-It's not possible to rewire `const` (see [#79](https://github.com/jhnns/rewire/issues/79)). This can probably be solved with [proxies](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Proxy) someday but requires further research. 
-
 **Transpilers**<br>
 Some transpilers, like babel, rename variables in order to emulate certain language features. Rewire will not work in these cases (see [#62](https://github.com/jhnns/rewire/issues/62)). A possible solution might be switching to [babel-plugin-rewire](https://github.com/speedskater/babel-plugin-rewire).
 

lib/index.js

@@ -13,4 +13,4 @@ function rewire(filename) {
 
 module.exports = rewire;
 
-delete require.cache[__filename];   // deleting self from module cache so the parent module is always up to date
+delete require.cache[__filename];   // deleting self from module cache so the parent module is always up to date

lib/moduleEnv.js

@@ -2,6 +2,7 @@
 
 var Module = require("module"),
     fs = require("fs"),
+    babelCore = require("babel-core"),
     coffee;
 
     // caching original wrapper
@@ -17,12 +18,28 @@ function load(targetModule) {
     currentModule = targetModule;
 
     registerExtensions();
+
     targetModule.load(targetModule.id);
 
     // This is only necessary if nothing has been required within the module
     reset();
 }
 
+function compile(targetModule, src, filename) {
+    nodeRequire = targetModule.require;
+    targetModule.require = requireProxy;
+    targetModule.filename = filename;
+    currentModule = targetModule;
+
+    var convertedSrc = babelCore.transform(stripBOM(src), {
+        plugins: ["transform-es2015-constants"]
+    });
+
+    targetModule._compile(convertedSrc.code, filename);
+
+    reset();
+}
+
 function reset() {
     Module.wrapper[0] = moduleWrapper0;
     Module.wrapper[1] = moduleWrapper1;
@@ -91,4 +108,5 @@ try {
 }
 
 exports.load = load;
+exports.compile = compile;
 exports.inject = inject;

lib/rewire.js

@@ -1,5 +1,6 @@
 var Module = require("module"),
     fs = require("fs"),
+    path = require("path"),
     getImportGlobalsSrc = require("./getImportGlobalsSrc.js"),
     getDefinePropertySrc = require("./getDefinePropertySrc.js"),
     detectStrictMode = require("./detectStrictMode.js"),
@@ -54,7 +55,13 @@ function internalRewire(parentModulePath, targetPath) {
     }
 
     moduleEnv.inject(prelude, appendix);
-    moduleEnv.load(targetModule);
+
+    if (targetPath.match(/\.coffee$/)) {
+        moduleEnv.load(targetModule);
+    } else {
+        moduleEnv.compile(targetModule, src, targetPath);
+    }
+
 
     return targetModule.exports;
 }