{ runCommand, concatText, writeText, hello, emptyFile }:
let
  stri = writeText "pathToTest";
  txt1 = stri "abc";
  txt2 = stri (builtins.toString hello);
  res = concatText "textToTest" [ txt1 txt2 ];
in
runCommand "test-concatPaths" { } ''
  diff -U3 <(cat ${txt1} ${txt2}) ${res}
  diff -U3 ${concatText "void" []} ${emptyFile}
  touch $out
''
