Stub oniguruma as reloading native modules are not well supported i…

…n Jest

Summary:
Use jest's functionality for mocking modules to always return
an empty object when `oniguruma` is required. This can be removed when
jestjs/jest#3552 is addressed.

Reviewed By: aaronabramov

Differential Revision: D7422795

fbshipit-source-id: c5a25511a058499ab2ad494a86f8772d7f4bc802

modules/nuclide-jest/emptyObject.js

@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) 2017-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.
+ *
+ * @flow
+ * @format
+ */
+
+// eslint-disable-next-line rulesdir/no-commonjs
+module.exports = {};

modules/nuclide-jest/jest.config.js

@@ -16,9 +16,14 @@
   rulesdir/no-commonjs: 0,
   */
 
+const path = require('path');
+
 module.exports = {
   testMatch: ['**/spec/**/*-spec.js'],
   transform: {
     '\\.js$': 'nuclide-jest/jestTransformer.js',
   },
+  moduleNameMapper: {
+    oniguruma: path.resolve(__dirname, 'emptyObject'),
+  },
 };