Make DataTable / DataInspector unit tests predictable

Summary: Having time / async / non-blocking behavior in components in unit tests is really annoying, as it makes unit tests async without an easy way to determine 'done'. This diff makes sure that DataTable & DataInspector don't break down their work in smaller tasks, but do everything block if they are running in a unit test.

Reviewed By: nikoant

Differential Revision: D28054487

fbshipit-source-id: 72c3b519e092ad69ed71eb1731e1fed80022f91f

desktop/flipper-plugin/src/utils/useInUnitTest().tsx

@@ -0,0 +1,16 @@
+/**
+ * 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
+ */
+
+/**
+ * Check if we are currently running a unit test.
+ * Use this hook to disable certain functionality that is probably not going to work as expected in the JSDom implementaiton
+ */
+export function useInUnitTest(): boolean {
+  return process.env.NODE_ENV === 'test';
+}