cling: add a smoke test

in

runCommand "cling-${unwrapped.version}" {

stdenv.mkDerivation {

  pname = "cling";

  version = unwrapped.version;

  nativeBuildInputs = [ makeWrapper ];

  inherit unwrapped flags;

  inherit (unwrapped) meta;

} ''

  dontUnpack = true;

  dontConfigure = true;

  buildPhase = ''

    runHook preBuild

    makeWrapper $unwrapped/bin/cling $out/bin/cling \

      --add-flags "$flags"

''

    runHook postBuild

  '';

  doCheck = true;

  checkPhase = ''

    runHook preCheck

    output=$($out/bin/cling <<EOF

    #include <iostream>

    std::cout << "hello world" << std::endl

    EOF

    )

    echo "$output" | grep -q "Type C++ code and press enter to run it"

    echo "$output" | grep -q "hello world"

    runHook postCheck

  '';

  dontInstall = true;

}