packager: AssetResolutionCache: tests + fix bug

Summary: Or, a case in point that Flow doesn't saves us from all the ills. I think it didn't complain because `MapWithDefaults` doesn't have proper typing. I'll deal with that separately.

Reviewed By: davidaurelio

Differential Revision: D5077707

fbshipit-source-id: c43623c5046d2dea9964685a44ad4877d060232e

packages/metro-bundler/src/node-haste/AssetResolutionCache.js

@@ -36,7 +36,7 @@ type Options = {|
   +platforms: Set<string>,
 |};
 
-type AssetInfo = {platform: ?string, fileName: string};
+type AssetInfo = {|platform: ?string, fileName: string|};
 type InfoByAssetName = Map<string, Array<AssetInfo>>;
 
 const EMPTY_ARRAY = [];
@@ -102,7 +102,7 @@ class AssetResolutionCache {
         continue;
       }
       getWithDefaultArray(results, assetData.assetName).push({
-        plaform: assetData.platform,
+        platform: assetData.platform,
         fileName,
       });
     }

packages/metro-bundler/src/node-haste/__tests__/AssetResolutionCache-test.js

@@ -0,0 +1,53 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @format
+ */
+
+'use strict';
+
+jest.disableAutomock();
+
+const AssetResolutionCache = require('../AssetResolutionCache');
+
+const MOCK_FILE_NAMES = [
+  'test@2x.ios.png',
+  'test@1x.ios.png',
+  'foo.jpg',
+  'bar.ios.png',
+  'test@1.5x.ios.png',
+  'foo@2x.jpg',
+  'test@3x.android.png',
+  'test.android.png',
+];
+
+describe('AssetResolutionCache', () => {
+  let fileNames, cache;
+
+  beforeEach(() => {
+    fileNames = [...MOCK_FILE_NAMES];
+    cache = new AssetResolutionCache({
+      assetExtensions: new Set(['png', 'jpg']),
+      getDirFiles: dirPath => (dirPath === '/assets' ? fileNames : []),
+      platforms: new Set(['ios', 'android']),
+    });
+  });
+
+  it('finds the correct assets', () => {
+    const results = cache.resolve('/assets', 'test.png', 'ios');
+    expect(results).toMatchSnapshot();
+  });
+
+  it('correctly clears out', () => {
+    cache.resolve('/assets', 'test.png', 'ios');
+    fileNames.push('test@3x.ios.png');
+    cache.clear();
+    const results = cache.resolve('/assets', 'test.png', 'ios');
+    expect(results).toMatchSnapshot();
+  });
+});

packages/metro-bundler/src/node-haste/__tests__/__snapshots__/AssetResolutionCache-test.js.snap

@@ -0,0 +1,18 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`AssetResolutionCache correctly clears out 1`] = `
+Array [
+  "test@2x.ios.png",
+  "test@1x.ios.png",
+  "test@1.5x.ios.png",
+  "test@3x.ios.png",
+]
+`;
+
+exports[`AssetResolutionCache finds the correct assets 1`] = `
+Array [
+  "test@2x.ios.png",
+  "test@1x.ios.png",
+  "test@1.5x.ios.png",
+]
+`;