Mocha 'before each hook' error message

I have the following message, just before a failing test

1) example "before each" hook: Error: timeout of 200ms exceeded. Ensure the done() callback is being called in this test. at null. (lib/runnable.js:170:19)

This error came only when I run the test case on my machine.If I run the same test case in another machine the test case is passing. why it happens.It's weird to see like this.

Any help please!!