I am currently evaluating if LAVA is the right tool for testing our custom flavour of a Raspbian Linux distro. The DUT is going to be a Raspberry Pi3 and I was trying to set it up in a minimal way using another Raspbi3 as a Server & Dispatcher (although first it seemed to work fine, when I followed the LAVA documentation and added the stretch backports sources in the apt list, my whole system crashed because of the depedencies). 

What is the best way to get a minimal setup running? I am also interested to know the hardware process (ideally everything we want to be automated). So, should the DUT be connected via a USB2serial cable?

A minimal setup depends on what you want to try first.
To start with LAVA, we advice to use qemu as DUT because this does not require any hardware.
In this case, a laptop is sufficient to test LAVA.

If you want to integrate a board inside LAVA then you will have to buy some hardware (PDU, serial connection, cables, ...)

Int he documentation you can read:
* https://staging.validation.linaro.org/static/docs/v2/advanced-installation.html?#other-infrastructure
* https://staging.validation.linaro.org/static/docs/v2/growing_your_lab.html


Other than that should that be connected to an SD multiplexer that burns the resulting .img after Jenkins finishes checking and generating it? 
Documentation is a bit tricky to go through as it covers many cases and there's not a simpler minimal tutorial. Also all the online blogs/posts seem to work for LAVA V1 only as a few things have changed.

So it will look something like this:
Linux .img (to be tested) -> SD Multiplexer(?) - DUT - USB2Serial -> LAVA Server & Dispatcher
                                                                                |
                                                                         LCD Screen

Are there anywhere some sample tests so I can get an idea of what I will be able to do? (Had already a look at the linaro .git but those seem 'too' basic; probably I've missed smth).

We don't have any example of a setup with a SD multiplexer because we don't have such hardware. If you know where we can buy that I'm really interested (and we might consider integrating this as a new deployment method in LAVA).


Cheers

-- 
Rémi Duraffort
LAVA Team
Linaro