Functional/regression testing for Java Applications working with files -

i'm trying find best way create automated testing functional/acceptance/regression testing java applications. applications work in way:

1. they read file given folder
2. they write new file in format content of input file.
3. they send database of information of processed files.
4. they wait until new file left in input folder.

this cyclic application, never stops.

new files/formats added continuously , several of our libraries shared formats. manual testing taking more , more cost each new format. files plain text files different format in way data saved.

we need way/tool automated functional/acceptance/regression tests (specially qa tests).

the question is: what tool/way of testing can used this?

i thinking in can left files in input folder , compare application creates in output folder expected file. don´t know if can done tool or if have make of entirely.

i use generic functional test automation framework , use set of libraries read/parse/compare files. familiar robot framework , there python libraries read/compare files (some embedded in robot itself, elsewhere). convenient , quite easy use qa tests. check out demo project start.

if prefer stick in java ecosystem, might want try cucumber-jvm or jbehave.