Add moduleNameMapper config

Summary: This adds the moduleNameMapper config which corresponds to the same config in flow.

public

Reviewed By: voideanvalue

Differential Revision: D2582879

fb-gh-sync-id: f116b86a7d4196c39faa366a521fe8401769b173

package.json

@@ -13,6 +13,10 @@
   "jest": {
     "scriptPreprocessor": "jestSupport/preprocessor.js",
     "setupEnvScriptFile": "jestSupport/env.js",
+    "moduleNameMapper": {
+      "^image![a-zA-Z0-9$_-]+$": "GlobalImageStub",
+      "^[./a-zA-Z0-9$_-]+\\.png$": "RelativeImageStub"
+    },
     "testPathIgnorePatterns": [
       "/node_modules/"
     ],