add nix development environment

.envrc

@@ -0,0 +1 @@
+use_flake

.gitignore

@@ -9,3 +9,4 @@ __pycache__
 build/
 dist/
 pip-wheel-metadata/
+.direnv

flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1696374741,
+        "narHash": "sha256-gt8B3G0ryizT9HSB4cCO8QoxdbsHnrQH+/BdKxOwqF0=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "8a4c17493e5c39769f79117937c79e1c88de6729",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-23.05",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,24 @@
+{
+  description = "A Nix-flake-based Python development environment";
+
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.05";
+
+  outputs = { self, nixpkgs }:
+    let
+      supportedSystems = [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
+      forEachSupportedSystem = f: nixpkgs.lib.genAttrs supportedSystems (system: f {
+        pkgs = import nixpkgs { inherit system; };
+      });
+    in
+    {
+      devShells = forEachSupportedSystem ({ pkgs }: {
+        default = pkgs.mkShell {
+          packages = with pkgs; [ python311 virtualenv borgbackup ] ++
+            (with pkgs.python311Packages; [ apprise pipx tox isort flexmock ]);
+          shellHook = ''
+            export PATH=~/.local/bin/:$PATH
+          '';
+        };
+      });
+    };
+}

setup.cfg

@@ -16,7 +16,7 @@ docstring-quotes = '''
 profile=black
 known_first_party = borgmatic
 line_length = 100
-skip = .tox
+skip = .tox,.direnv
 
 [codespell]
 skip = .git,.tox,build