[joegosse]

Is dieharder considered as the industry standard tool for testing randomness? Is it commonly used by experts?

https://www.phy.duke.edu/~rgb/General/dieharder.php

[eutectic]

Dieharder works OK, and you can easily install it on Ubuntu as a command-line tool. PractRand and TestU01 are more stringent and give you more knobs to play with.