{
  config,
  lib,
  realPkgs,
  ...
}:

lib.mkIf config.test.enableBig {
  programs = {
    carapace.enable = true;
    fish.enable = true;
  };

  nixpkgs.overlays = [ (self: super: { inherit (realPkgs) carapace; }) ];

  nmt.script =
    let
      needsCompletionOverrides = lib.versionOlder realPkgs.fish.version "4.0.0";
    in
    ''
      assertFileExists home-files/.config/fish/config.fish
      assertFileRegex home-files/.config/fish/config.fish \
        '/nix/store/.*carapace.*/bin/carapace _carapace fish \| source'
    ''
    + (lib.optionalString needsCompletionOverrides ''
      # Check whether completions are overridden, necessary for fish < 4.0
      assertFileExists home-files/.config/fish/completions/git.fish
      assertFileContent home-files/.config/fish/completions/git.fish /dev/null
    '')
    + (lib.optionalString (!needsCompletionOverrides) ''
      assertPathNotExists home-files/.config/fish/completions
    '');
}