nixos-rebuild-ng: add devShell

pkgs/by-name/ni/nixos-rebuild-ng/README.md

@@ -53,6 +53,38 @@ an attempt of the rewrite.
 
 And use `nixos-rebuild-ng` instead of `nixos-rebuild`.
 
+## Development
+
+Run:
+
+```console
+nix-build -A nixos-rebuild-ng.tests.ci
+```
+
+The command above will run the unit tests and linters, and also check if the
+code is formatted. However, sometimes is more convenient to run just a few
+tests to debug, in this case you can run:
+
+```console
+nix-shell -A nixos-rebuild-ng.devShell
+```
+
+The command above should automatically put you inside `src` directory, and you
+can run:
+
+```console
+# run program
+python -m nixos_rebuild
+# run tests
+python -m pytest
+# check types
+mypy .
+# fix lint issues
+ruff check --fix .
+# format code
+ruff format .
+```
+
 ## Current caveats
 
 - For now we will install it in `nixos-rebuild-ng` path by default, to avoid

pkgs/by-name/ni/nixos-rebuild-ng/package.nix

@@ -1,9 +1,9 @@
 {
   lib,
   installShellFiles,
+  mkShell,
   nix,
   nixos-rebuild,
-  nixos-rebuild-ng,
   python3,
   runCommand,
   withNgSuffix ? true,
@@ -60,37 +60,42 @@ python3.pkgs.buildPythonApplication rec {
 
   pytestFlagsArray = [ "-vv" ];
 
-  # NOTE: this is a CI test rather than a build-time test because we want to
-  # keep the build closures small
-  passthru.tests = {
-    ci =
-      runCommand "${pname}-ci"
-        {
-          nativeBuildInputs = [
-            nixos-rebuild-ng # to trigger build
-            (python3.withPackages (
-              ps: with ps; [
-                mypy
-                pytest
-                ruff
-                types-tabulate
-              ]
-            ))
-          ];
-        }
-        ''
-          export RUFF_CACHE_DIR="$(mktemp -d)"
-
-          echo -e "\x1b[32m## run mypy\x1b[0m"
-          mypy ${src}
-          echo -e "\x1b[32m## run ruff\x1b[0m"
-          ruff check ${src}
-          echo -e "\x1b[32m## run ruff format\x1b[0m"
-          ruff format --check ${src}
-
-          touch $out
+  passthru =
+    let
+      python-with-pkgs = python3.withPackages (
+        ps: with ps; [
+          mypy
+          pytest
+          ruff
+          types-tabulate
+          # dependencies
+          tabulate
+        ]
+      );
+    in
+    {
+      devShell = mkShell {
+        packages = [ python-with-pkgs ];
+        shellHook = ''
+          cd pkgs/by-name/ni/nixos-rebuild-ng/src || true
         '';
-  };
+      };
+
+      # NOTE: this is a passthru test rather than a build-time test because we
+      # want to keep the build closures small
+      tests.ci = runCommand "${pname}-ci" { nativeBuildInputs = [ python-with-pkgs ]; } ''
+        export RUFF_CACHE_DIR="$(mktemp -d)"
+
+        echo -e "\x1b[32m## run mypy\x1b[0m"
+        mypy ${src}
+        echo -e "\x1b[32m## run ruff\x1b[0m"
+        ruff check ${src}
+        echo -e "\x1b[32m## run ruff format\x1b[0m"
+        ruff format --check ${src}
+
+        touch $out
+      '';
+    };
 
   meta = {
     description = "Rebuild your NixOS configuration and switch to it, on local hosts and remote";

pkgs/by-name/ni/nixos-rebuild-ng/src/nixos_rebuild/__init__.py

@@ -231,7 +231,3 @@ def main() -> None:
             raise ex
         else:
             sys.exit(str(ex))
-
-
-if __name__ == "__main__":
-    main()

pkgs/by-name/ni/nixos-rebuild-ng/src/nixos_rebuild/__main__.py

@@ -0,0 +1,4 @@
+from . import main
+
+if __name__ == "__main__":
+    main()