With no familiarity of the subject, I see a lot of DCP player programs. What do you mean by "test it"?

I'm not sure what parent means, but I've projected quite a few DCP films made by individuals / beginners at movie festivals - hand often the technical quality is heart-breakingly bad: the colour, resolution, encoding/compression and sometimes frame rate can be off. Most of these are fixable if you know what you are doing.

But it takes a lot of experience to imagine what a frame that looks great on a ~24 inch monitor will look like when projected in a theater.

I would strongly recommend that anyone dreaming to screen something in cinemas make a deal with their local cinema in order to do test screenings - to check picture and sound. Just like with anything else, there's no substitute for testing under "real" conditions.

Note that most(?) cinema setups will happily take some form of digital audio/video signal and run it through dolby surround and project it - so you don't have to start testing with a DCP file. But you certainly should test that in a cinema before distribution.

Also note that the "player" part of a fixed installation might have quirks/bugs that software that's more easily updated might work around (think mplayer vs a cheap old DVD player).

TIL, thanks for the clarification and information. Definitely filed away.