disable tests at compile time

[Nilson Silva <nilsonfsilva@hotmail.com>]

Hello guys.
I recently joined the Rust team. So, as I'm still getting the hang of doing things, 
could anyone tell me the best way to disable compile-time tests, to avoid errors.

upstream, deleted a directory needed for testing. So to avoid compile 
time errors I would like to disable it.

in python we configure debian/rules
with override_dh_auto_test?
In rust how do we do this:

this is the project
https://github.com/Roughsketch/imagesize

thanks!
Nilson F. Silva