# Tokio Authors - Unit Testing (Highlights)  ## Highlights - However, internally, the time-related functionality of tokio supports pausing and resuming time. Pausing time has the effect that any time-related future may become ready early. ([View Highlight](https://read.readwise.io/read/01kdan01mmgznpakhz3hkma0zk)) ^969702378 `tokio::time::pause()` - For unit tests, it is often useful to run with paused time throughout. This can be achieved simply by setting the macro argument `start_paused` to `true` ([View Highlight](https://read.readwise.io/read/01kdamzqt0td6k97tenc01qhv7)) ^969702374 - To unit test the client connection handler, a [`tokio_test::io::Builder`](https://docs.rs/tokio-test/latest/tokio_test/io/struct.Builder.html) can be used as a mock ([View Highlight](https://read.readwise.io/read/01kdan1w4e67gbhdpdwd6dfp3r)) ^969702414