From 353bfba978d66d11bb736f1c0771132b65e7693c Mon Sep 17 00:00:00 2001
From: Jean Lauliac <jeanlauliac@fb.com>
Date: Wed, 10 May 2017 04:34:10 -0700
Subject: [PATCH] packager: ResolutionRequest: simplify asset resolution

Summary: I think we don't really need to check the directory beforehand, the function to find asset will just return an empty array. As for the error message, I tried adding a require of an asset file somewhere, but due to the way the ResolutionRequest algo work, it generates a final error message that unrealted ("Directory ... does not exist", instead of the "asset does not exist"). I plan to revamp the way errors are handled such as the error message clearly identifies what file paths have been inspected.

Reviewed By: davidaurelio

Differential Revision: D5028118

fbshipit-source-id: 496472001c0a3d4192bfef4a0c8a0dc8a9a0fa82
---
 .../DependencyGraph/ResolutionRequest.js      | 49 ++++++++++---------
 1 file changed, 25 insertions(+), 24 deletions(-)

diff --git a/packages/metro-bundler/src/node-haste/DependencyGraph/ResolutionRequest.js b/packages/metro-bundler/src/node-haste/DependencyGraph/ResolutionRequest.js
index 170d8e05..f4468fbe 100644
--- a/packages/metro-bundler/src/node-haste/DependencyGraph/ResolutionRequest.js
+++ b/packages/metro-bundler/src/node-haste/DependencyGraph/ResolutionRequest.js
@@ -500,30 +500,7 @@ class ResolutionRequest<TModule: Moduleish, TPackage: Packageish> {
 
   _loadAsFile(potentialModulePath: string, fromModule: TModule, toModule: string): TModule {
     if (this._options.helpers.isAssetFile(potentialModulePath)) {
-      const dirname = path.dirname(potentialModulePath);
-      if (!this._options.dirExists(dirname)) {
-        throw new UnableToResolveError(
-          fromModule,
-          toModule,
-          `Directory ${dirname} doesn't exist`,
-        );
-      }
-
-      const {name, type} = getAssetDataFromName(potentialModulePath, this._options.platforms);
-
-      let pattern = '^' + name + '(@[\\d\\.]+x)?';
-      if (this._options.platform != null) {
-        pattern += '(\\.' + this._options.platform + ')?';
-      }
-      pattern += '\\.' + type + '$';
-
-      const assetFiles = this._options.matchFiles(dirname, new RegExp(pattern));
-      // We arbitrarly grab the lowest, because scale selection will happen
-      // somewhere else. Always the lowest so that it's stable between builds.
-      const assetFile = getArrayLowestItem(assetFiles);
-      if (assetFile) {
-        return this._options.moduleCache.getAssetModule(assetFile);
-      }
+      return this._loadAsAssetFile(potentialModulePath, fromModule, toModule);
     }
 
     let file;
@@ -567,6 +544,30 @@ class ResolutionRequest<TModule: Moduleish, TPackage: Packageish> {
     return this._options.moduleCache.getModule(file);
   }
 
+  _loadAsAssetFile(potentialModulePath: string, fromModule: TModule, toModule: string): TModule {
+    const {name, type} = getAssetDataFromName(potentialModulePath, this._options.platforms);
+
+    let pattern = '^' + name + '(@[\\d\\.]+x)?';
+    if (this._options.platform != null) {
+      pattern += '(\\.' + this._options.platform + ')?';
+    }
+    pattern += '\\.' + type + '$';
+
+    const dirname = path.dirname(potentialModulePath);
+    const assetFiles = this._options.matchFiles(dirname, new RegExp(pattern));
+    // We arbitrarly grab the lowest, because scale selection will happen
+    // somewhere else. Always the lowest so that it's stable between builds.
+    const assetFile = getArrayLowestItem(assetFiles);
+    if (assetFile) {
+      return this._options.moduleCache.getAssetModule(assetFile);
+    }
+    throw new UnableToResolveError(
+      fromModule,
+      toModule,
+      `Directory \`${dirname}' doesn't contain asset \`${name}'`,
+    );
+  }
+
   _loadAsDir(potentialDirPath: string, fromModule: TModule, toModule: string): TModule {
     if (!this._options.dirExists(potentialDirPath)) {
       throw new UnableToResolveError(