Show execution time of whole test class

[dbardbar]

Description

Add ability to show execution time of whole test class.

Additional information

Showing test class time has several benefits:

1. Show full execution time, including time spent in @BeforeAll or @afterall
2. Ability to see at high-level where time is wasted, especially if having hundreds of tests, spread over several test classes. Looking at the high-level per-class time helps to find and optimize test run time.

[radarsh]

I've been thinking of an idea to print the top-5 or top-n slow tests across the whole project. This along with a few other metrics could form a statistics summary.

[giriprashant7891]

I would also appreciate this feature. Currently, I'm unable to track the time taken by Springboot to initiate the context for the class, as the tracking is only done at a test level. If we are able to track at the class level, along with the initialization time, that would be fantastic!