Fix providesModuleNodeModules behavior to be more deterministic.

Currently, the `providesModuleNodeModules` option allows for specifying an array of package names, that the packager will look for within node_modules, no matter how deep they're nested, and treat them as packages that use the `@providesModule` pragma.

In reality, this is not actually the behavior we want.

npm, because of how it handles dependencies, can do all kinds of arbitrary nesting of packages when `npm install` is run. This causes a problem for how we deal with `providesModuleNodeModules`. Specifically...take `fbjs`. Currently, React Native relies on using the Haste version of `fbjs` (will be resolved in facebook#5084). Thus if npm installs multiple copies of fbjs...which is a very common thing for it to do (as can be seen by this list of issues: https://github.com/facebook/react-native/issues?utf8=%E2%9C%93&q=naming+collision+detected), we get into a state where the packager fails and says that we have a naming collision.

Really, the behavior we want is for the packager to treat only a *single* copy of a given package, that we specify in the `Resolver` in the `providesModuleNodeModules` option, as the package that it uses when trying to resolve Haste modules.

This PR provides that behavior, by changing `providesModuleNodeModules` from a list of strings to a list of objects that have a `name` key, specifying the package name, as well as a `parent` key. If `parent` is null, it will look for the package at the top level (directly under `node_modules`). If `parent` is specified, it will use the package that is nested under that parent as the Haste module.

To anyone who reads this PR and is familiar with the differences between npm2 and npm3 -- this solution works under both, given the fact that we are now shipping the NPM Shrinkwrap file with React Native when it's installed through `npm`. In both the npm2 and npm3 case, node_modules specified by RN's package.json are nested underneath `react-native` in node_modules, thus allowing us to specify, for example, that we want to use React Native's copy of `fbjs` (not any other copy that may be installed) as the module used by the packager to resolve any `requires` that reference a module in `fbjs`.

packager/react-packager/src/DependencyResolver/DependencyGraph/DependencyGraphHelpers.js

@@ -1,4 +1,4 @@
- /**
+/**
  * Copyright (c) 2015-present, Facebook, Inc.
  * All rights reserved.
  *
@@ -16,16 +16,48 @@ class DependencyGraphHelpers {
     this._assetExts = assetExts;
   }
 
+  /**
+   * This method has three possible outcomes:
+   *
+   * 1) A file is not in "node_modules" at all (some type of file in the project).
+   * 2) The file is in "node_modules", and it's contained in one of the
+   * "providesModuleNodeModules" packages.
+   * 3) It's in "node_modules" but not in a "providesModuleNodeModule" package,
+   * so it's just a normal node_module.
+   *
+   * An item in the `providesModuleNodeModule` is an object containing two keys:
+   *  * "name" - the package name
+   *  * "parent" - if a string, it's the name of the parent package of the module in
+   *  the dep tree. If null, it signifies that we should look for this package at
+   *  the top level of the module tree.
+   */
   isNodeModulesDir(file) {
-    const index = file.lastIndexOf('/node_modules/');
+    const index = file.indexOf('/node_modules/');
     if (index === -1) {
       return false;
     }
 
-    const parts = file.substr(index + 14).split(path.sep);
-    const dirs = this._providesModuleNodeModules;
-    for (let i = 0; i < dirs.length; i++) {
-      if (parts.indexOf(dirs[i]) > -1) {
+    const lastIndex = file.lastIndexOf('/node_modules/');
+    const fullPathParts = file.substr(index + 14).split(path.sep);
+    const packageParts = file.substr(lastIndex + 14).split(path.sep);
+    const packageName = packageParts[0];
+
+    const modules = this._providesModuleNodeModules;
+    for (let i = 0; i < modules.length; i++) {
+      const providesModuleNodeModule = modules[i];
+      const providesModulePackageName = providesModuleNodeModule.name;
+      const providesModuleParent = providesModuleNodeModule.parent;
+
+      let parent = null;
+      // if the top level package name is not the same as what we already
+      // computed the "packageName" to be, then make sure we record that
+      // that package is the parent
+      if (fullPathParts[0] !== packageName) {
+        parent = fullPathParts[0];
+      }
+
+      if (providesModulePackageName === packageName &&
+          providesModuleParent === parent) {
         return false;
       }
     }

packager/react-packager/src/DependencyResolver/DependencyGraph/__tests__/DependencyGraph-test.js

@@ -90,9 +90,9 @@ describe('DependencyGraph', function() {
       cache: new Cache(),
       fileWatcher,
       providesModuleNodeModules: [
-        'haste-fbjs',
-        'react-haste',
-        'react-native',
+        { name: 'haste-fbjs', parent: null },
+        { name: 'react-haste', parent: null },
+        { name: 'react-native', parent: null },
         // Parse requires AsyncStorage. They will
         // change that to require('react-native') which
         // should work after this release and we can

packager/react-packager/src/Resolver/index.js

@@ -85,14 +85,21 @@ class Resolver {
           (opts.blacklistRE && opts.blacklistRE.test(filepath));
       },
       providesModuleNodeModules: [
-        'fbjs',
-        'react',
-        'react-native',
+        // Use the project's installed version of react-native
+        // as the "haste" version of `react-native`
+        // (and ignore any nested copies);
+        { name: 'react-native', parent: null },
+        // Use the react peerDep for the "haste"
+        // version of `react`.
+        { name: 'react', parent: null },
+        // We only want to use the fbjs underneath react-native
+        // as the "haste" version of `fbjs`.
+        { name: 'fbjs', parent: 'react-native'},
         // Parse requires AsyncStorage. They will
         // change that to require('react-native') which
         // should work after this release and we can
         // remove it from here.
-        'parse',
+        { name: 'parse', parent: null },
       ],
       platforms: ['ios', 'android'],
       preferNativePlatform: true,