nix-your-shell: add module

modules/misc/news.nix

@@ -1827,6 +1827,16 @@ in {
           as systemd services.
         '';
       }
+
+      {
+        time = "2024-12-01T19:17:40+00:00";
+        message = ''
+          A new module is available: 'programs.nix-your-shell'.
+
+          nix-your-shell is a wrapper for `nix develop` or `nix-shell` to retain
+          the same shell inside the new environment.
+        '';
+      }
     ];
   };
 }

modules/modules.nix

@@ -176,6 +176,7 @@ let
     ./programs/nh.nix
     ./programs/nheko.nix
     ./programs/nix-index.nix
+    ./programs/nix-your-shell.nix
     ./programs/nnn.nix
     ./programs/noti.nix
     ./programs/notmuch.nix

modules/programs/nix-your-shell.nix

@@ -0,0 +1,55 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  cfg = config.programs.nix-your-shell;
+
+in {
+  meta.maintainers = [ maintainers.terlar ];
+
+  options.programs.nix-your-shell = {
+    enable = mkEnableOption ''
+      {command}`nix-your-shell`, a wrapper for `nix develop` or `nix-shell`
+      to retain the same shell inside the new environment'';
+
+    package = mkPackageOption pkgs "nix-your-shell" { };
+
+    enableFishIntegration = mkEnableOption "Fish integration" // {
+      default = true;
+    };
+
+    enableNushellIntegration = mkEnableOption "Nushell integration" // {
+      default = true;
+    };
+
+    enableZshIntegration = mkEnableOption "Zsh integration" // {
+      default = true;
+    };
+  };
+
+  config = mkIf cfg.enable {
+    home.packages = [ cfg.package ];
+
+    programs = {
+      fish.interactiveShellInit = mkIf cfg.enableFishIntegration ''
+        ${cfg.package}/bin/nix-your-shell fish | source
+      '';
+
+      nushell = mkIf cfg.enableNushellIntegration {
+        extraEnv = ''
+          ${cfg.package}/bin/nix-your-shell nu | save --force ${config.xdg.cacheHome}/nix-your-shell/init.nu
+        '';
+
+        extraConfig = ''
+          source ${config.xdg.cacheHome}/nix-your-shell/init.nu
+        '';
+      };
+
+      zsh.initExtra = mkIf cfg.enableZshIntegration ''
+        ${cfg.package}/bin/nix-your-shell zsh | source /dev/stdin
+      '';
+    };
+  };
+}

tests/default.nix

@@ -118,6 +118,7 @@ in import nmtSrc {
     ./modules/programs/newsboat
     ./modules/programs/nheko
     ./modules/programs/nix-index
+    ./modules/programs/nix-your-shell
     ./modules/programs/nnn
     ./modules/programs/nushell
     ./modules/programs/oh-my-posh

tests/modules/programs/nix-your-shell/default.nix

@@ -0,0 +1 @@
+{ nix-your-shell-enable-shells = ./enable-shells.nix; }

tests/modules/programs/nix-your-shell/enable-shells.nix

@@ -0,0 +1,48 @@
+{ pkgs, config, ... }:
+
+{
+  programs = {
+    nix-your-shell = {
+      enable = true;
+      enableFishIntegration = true;
+      enableNushellIntegration = true;
+      enableZshIntegration = true;
+    };
+    fish.enable = true;
+    nushell.enable = true;
+    zsh.enable = true;
+  };
+
+  test.stubs = {
+    nix-your-shell = { };
+    nushell = { };
+    zsh = { };
+  };
+
+  nmt.script = let
+    nushellConfigDir = if pkgs.stdenv.isDarwin && !config.xdg.enable then
+      "home-files/Library/Application Support/nushell"
+    else
+      "home-files/.config/nushell";
+  in ''
+    assertFileExists home-files/.config/fish/config.fish
+    assertFileContains \
+      home-files/.config/fish/config.fish \
+      '@nix-your-shell@/bin/nix-your-shell fish | source'
+
+    assertFileExists ${nushellConfigDir}/config.nu
+    assertFileContains \
+      ${nushellConfigDir}/config.nu \
+      'source ${config.xdg.cacheHome}/nix-your-shell/init.nu'
+
+    assertFileExists ${nushellConfigDir}/env.nu
+    assertFileContains \
+      ${nushellConfigDir}/env.nu \
+      '@nix-your-shell@/bin/nix-your-shell nu | save --force ${config.xdg.cacheHome}/nix-your-shell/init.nu'
+
+    assertFileExists home-files/.zshrc
+    assertFileContains \
+      home-files/.zshrc \
+      '@nix-your-shell@/bin/nix-your-shell zsh | source /dev/stdin'
+  '';
+}