Yarn start Failed with "Error: Unable to resolve module react-redux" (#883)

Summary:
Pull Request resolved: https://github.com/facebook/flipper/pull/883

https://github.com/facebook/flipper/issues/835

Reviewed By: passy

Differential Revision: D20363818

fbshipit-source-id: 66b7cb7236c7b066db32473a9e993ba2ace529bc

scripts/prepare-watchman-config.js

@@ -0,0 +1,30 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+const path = require('path');
+const util = require('util');
+const {exists: existsImport, copyFile} = require('fs');
+const exists = util.promisify(existsImport);
+
+const rootDir = path.resolve(__dirname, '..');
+const hasGit = exists(path.join(rootDir, '.git'));
+
+async function prepareWatchmanConfig(dir) {
+  const hasWatchmanConfig = exists(path.join(dir, '.watchmanconfig'));
+  if ((await hasGit) && !(await hasWatchmanConfig)) {
+    console.log(`Creating .watchmanconfig in ${dir}`);
+    await util.promisify(copyFile)(
+      path.join(dir, '_watchmanconfig'),
+      path.join(dir, '.watchmanconfig'),
+    );
+  }
+}
+
+prepareWatchmanConfig(rootDir);
+prepareWatchmanConfig(path.join(rootDir, 'static'));