From 70af3b126a0ca281526e328f32c4009a2804aa21 Mon Sep 17 00:00:00 2001
From: Robert Helgesson <robert@rycee.net>
Date: Sat, 1 Feb 2020 20:59:49 +0100
Subject: [PATCH] ci: add format script and use in CI pipeline

The format script can be used to automatically format the Nix source
files and also verify that the files are formatted using the `-c`
command argument.

At the moment some files are exempt from the formatting to avoid
causing merge conflicts in active pull requests.

Finally, update the contribution guidelines to note that `nixfmt`
should be used.
---
 .travis.yml     |  1 +
 CONTRIBUTING.md | 17 +++++++-----
 format          | 70 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 81 insertions(+), 7 deletions(-)
 create mode 100755 format

diff --git a/.travis.yml b/.travis.yml
index df9c468b..e0712e1e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,5 +8,6 @@ before_script:
   - mkdir -m 0755 -p /nix/var/nix/{profiles,gcroots}/per-user/$USER
 
 script:
+  - ./format -c
   - nix-shell . -A install
   - nix-shell tests -A run.all
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index d441aef0..8e64b3b4 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -91,12 +91,15 @@ In addition to the above commit message guidelines, try to follow the
 
 ### Style guidelines ###
 
-The code in Home Manager should follow the [Nixpkgs syntax
-guidelines][]. Note, we prefer `lowerCamelCase` for variable and
-attribute names with the accepted exception of variables directly
-referencing packages in Nixpkgs which use a hyphenated style. For
-example, the Home Manager option `services.gpg-agent.enableSshSupport`
-references the `gpg-agent` package in Nixpkgs.
+The code in Home Manager is formatted by the [nixfmt][] tool and the
+formatting is checked in the pull request tests. Run the `format` tool
+inside the project repository before submitting your pull request.
+
+Note, we prefer `lowerCamelCase` for variable and attribute names with
+the accepted exception of variables directly referencing packages in
+Nixpkgs which use a hyphenated style. For example, the Home Manager
+option `services.gpg-agent.enableSshSupport` references the
+`gpg-agent` package in Nixpkgs.
 
 ### News ###
 
@@ -158,4 +161,4 @@ If you do have a change worthy of a news entry then please add one in
 [create a pull request]: https://help.github.com/articles/creating-a-pull-request/
 [seven rules]: https://chris.beams.io/posts/git-commit/#seven-rules
 [`news.nix`]: https://github.com/rycee/home-manager/blob/master/modules/misc/news.nix
-[Nixpkgs syntax guidelines]: https://nixos.org/nixpkgs/manual/#sec-syntax
+[nixfmt]: https://github.com/serokell/nixfmt/
diff --git a/format b/format
new file mode 100755
index 00000000..539ae60d
--- /dev/null
+++ b/format
@@ -0,0 +1,70 @@
+#! /usr/bin/env nix-shell
+#! nix-shell -i bash -p findutils nixfmt
+
+CHECK_ARG=
+
+case $1 in
+    -h)
+        echo "$0 [-c]"
+        ;;
+    -c)
+        CHECK_ARG=-c
+        ;;
+esac
+
+# The first block of excludes are files where nixfmt does a poor job,
+# IMHO. The second block of excludes are files touched by open pull
+# requests and we want to avoid merge conflicts.
+find . -name '*.nix' \
+  ! -path ./modules/programs/irssi.nix \
+  \
+  ! -path ./home-manager/default.nix \
+  ! -path ./home-manager/home-manager.nix \
+  ! -path ./modules/accounts/email.nix \
+  ! -path ./modules/default.nix \
+  ! -path ./modules/files.nix \
+  ! -path ./modules/home-environment.nix \
+  ! -path ./modules/lib/default.nix \
+  ! -path ./modules/lib/file-type.nix \
+  ! -path ./modules/lib/types.nix \
+  ! -path ./modules/manual.nix \
+  ! -path ./modules/misc/dconf.nix \
+  ! -path ./modules/misc/gtk.nix \
+  ! -path ./modules/misc/news.nix \
+  ! -path ./modules/misc/nixpkgs.nix \
+  ! -path ./modules/misc/xdg.nix \
+  ! -path ./modules/modules.nix \
+  ! -path ./modules/programs/afew.nix \
+  ! -path ./modules/programs/alot.nix \
+  ! -path ./modules/programs/bash.nix \
+  ! -path ./modules/programs/emacs.nix \
+  ! -path ./modules/programs/firefox.nix \
+  ! -path ./modules/programs/fish.nix \
+  ! -path ./modules/programs/gpg.nix \
+  ! -path ./modules/programs/lesspipe.nix \
+  ! -path ./modules/programs/neovim.nix \
+  ! -path ./modules/programs/ssh.nix \
+  ! -path ./modules/programs/tmux.nix \
+  ! -path ./modules/programs/vscode.nix \
+  ! -path ./modules/programs/zsh.nix \
+  ! -path ./modules/services/gpg-agent.nix \
+  ! -path ./modules/services/kbfs.nix \
+  ! -path ./modules/services/keybase.nix \
+  ! -path ./modules/services/mpd.nix \
+  ! -path ./modules/services/sxhkd.nix \
+  ! -path ./modules/services/window-managers/i3.nix \
+  ! -path ./modules/systemd.nix \
+  ! -path ./nix-darwin/default.nix \
+  ! -path ./tests/default.nix \
+  ! -path ./tests/modules/home-environment/default.nix \
+  ! -path ./tests/modules/home-environment/session-variables.nix \
+  ! -path ./tests/modules/programs/gpg/override-defaults.nix \
+  ! -path ./tests/modules/programs/tmux/default.nix \
+  ! -path ./tests/modules/programs/tmux/disable-confirmation-prompt.nix \
+  ! -path ./tests/modules/programs/tmux/secure-socket-enabled.nix \
+  ! -path ./tests/modules/programs/zsh/session-variables.nix \
+  ! -path ./tests/modules/services/sxhkd/service.nix \
+  ! -path ./tests/modules/systemd/default.nix \
+  ! -path ./tests/modules/systemd/services.nix \
+  ! -path ./tests/modules/systemd/session-variables.nix \
+  -exec nixfmt $CHECK_ARG {} +