From e27418ca3f1f4700a457145de899c0d67343ee77 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Felix=20Geisend=C3=B6rfer?= <felix@debuggable.com>
Date: Mon, 13 Dec 2010 23:56:16 +0100
Subject: [PATCH] Prefer require.cache over native module cache

This patch changes node's module loading behavior so that the
require.cache is always the first place to consider when loading a
module.

The motivation for this change is to help people who are writing
focused tests for their node.js applications, and need a mechanism
to inject test doubles to replace native node.js modules.
---
 src/node.js                       |  6 +++---
 test/simple/test-require-cache.js | 22 ++++++++++++++++++++++
 2 files changed, 25 insertions(+), 3 deletions(-)
 create mode 100644 test/simple/test-require-cache.js

diff --git a/src/node.js b/src/node.js
index 334d8c5ee..43ccdb032 100644
--- a/src/node.js
+++ b/src/node.js
@@ -238,6 +238,9 @@
       var id = resolved[0];
       var filename = resolved[1];
 
+      var cachedModule = moduleCache[filename];
+      if (cachedModule) return cachedModule.exports;
+
       // With natives id === request
       // We deal with these first
       if (natives[id]) {
@@ -253,9 +256,6 @@
         return requireNative(id);
       }
 
-      var cachedModule = moduleCache[filename];
-      if (cachedModule) return cachedModule.exports;
-
       var module = new Module(id, parent);
       moduleCache[filename] = module;
       module.load(filename);
diff --git a/test/simple/test-require-cache.js b/test/simple/test-require-cache.js
new file mode 100644
index 000000000..a069d0a79
--- /dev/null
+++ b/test/simple/test-require-cache.js
@@ -0,0 +1,22 @@
+var common = require('../common');
+var assert = require('assert');
+
+(function testInjectFakeModule() {
+  var relativePath = '../fixtures/semicolon';
+  var absolutePath = require.resolve(relativePath);
+  var fakeModule = {};
+
+  require.cache[absolutePath] = {exports: fakeModule};
+
+  assert.strictEqual(require(relativePath), fakeModule);
+})();
+
+
+(function testInjectFakeNativeModule() {
+  var relativePath = 'fs';
+  var fakeModule = {};
+
+  require.cache[relativePath] = {exports: fakeModule};
+
+  assert.strictEqual(require(relativePath), fakeModule);
+})();