Or, getting back to the OP's original request (but using interpolation),

push @inputfiles,
    "$inputPathPrefix/test4.xml",
    "$inputPathPrefix/test5.xml",
    "$inputPathPrefix/test6.xml",
    "$inputPathPrefix/test7.xml",
    ;
[download]

This is my personal favorite way to append to an array.

I do not normally build file names this way, preferring something like the old File::Path. Though, as others have pointed out, there are sexier way to do things these days.