anchor.diff:      doxygen perl  # (optional) api docs
       pythonPackages.sphinx pythonPackages.python  # (optional) documentation -> doc/INSTALL
       bash-completion  # (optional) dependency to install bash completion
  -    emacs  # (optional) to byte compile emacs code
  +    emacs  # (optional) to byte compile emacs code, also needed for tests
       ruby  # (optional) ruby bindings
       which dtach openssl bash  # test dependencies
     ]
  
positive.code: 
    src = fetchurl {
      url = "https://notmuchmail.org/releases/${name}.tar.gz";
      sha256 = "0xh8vq2sa7r07xb3n13drc6gdiqhcgl0pj0za5xj43qkiwpikls0";
    };
  
    nativeBuildInputs = [ pkgconfig ];
  
negative.code: with stdenv.lib;
  
  stdenv.mkDerivation rec {
    version = "0.28";
    name = "notmuch-${version}";
  
    passthru = {
  