Testing asynchronous code in Elixir

I want to test a function which is using Task.async In order to make my test pass, I need to make it sleep for 100ms before assertions, otherwise the test process is killed before the async task is executed. Is there a better way? EDITED, adding code samples : The code I would like to test (roughly) : def search(params) do RateLimiter.rate_limit(fn -> parsed_params = ExTwitter.Parser.parse_request