From 0b6241abda2b2a2da8cdef98f681bc1467085298 Mon Sep 17 00:00:00 2001
From: Erik Hennig <github@erik-hennig.me>
Date: Fri, 8 Nov 2024 22:28:04 +0100
Subject: [PATCH] feat: generate auto-completion in flake build (#65)

---
 .github/workflows/ci.yml    |  7 +++++
 flake.nix                   |  7 +++++
 tests/shell_completions.exp | 56 +++++++++++++++++++++++++++++++++++++
 3 files changed, 70 insertions(+)
 create mode 100755 tests/shell_completions.exp

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e5de8b0..ff9f53b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -77,6 +77,13 @@ jobs:
         run: ./result/bin/rip --version
       - name: Test default app
         run: nix run . -- --help
+      - name: Test shell completions
+        run: |
+          # pre-fetch bash-completion then get its path in the store
+          nix build nixpkgs#bash-completion
+          export BASH_COMPLETION_PKG=$(nix path-info nixpkgs#bash-completion)
+          # use bashInteractive from nixpkgs because default bash is too old for bash-completion on macOS
+          nix shell . nixpkgs#expect nixpkgs#bash-completion nixpkgs#bashInteractive -c tests/shell_completions.exp
 
   release-please:
     name: Execute release chores
diff --git a/flake.nix b/flake.nix
index 38c3f1c..2b92f8e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -18,6 +18,13 @@
         naersk' = pkgs.callPackage naersk {};
         rip2 = naersk'.buildPackage {
           src = ./.;
+          nativeBuildInputs = [ pkgs.installShellFiles ];
+          postInstall = ''
+           installShellCompletion --cmd rip \
+             --bash <($out/bin/rip completions bash) \
+             --fish <($out/bin/rip completions fish) \
+             --zsh <($out/bin/rip completions zsh)
+          '';
         };
       in
       with pkgs;
diff --git a/tests/shell_completions.exp b/tests/shell_completions.exp
new file mode 100755
index 0000000..e01c1c3
--- /dev/null
+++ b/tests/shell_completions.exp
@@ -0,0 +1,56 @@
+#!/usr/bin/env expect
+
+# Script based on https://stackoverflow.com/a/42085887
+# If you are unfamiliar with expect scripts, this guide might be helpful:
+# https://gist.github.com/ksafranski/6294378
+
+# Disable debug options
+log_user 0
+exp_internal 0
+
+set prompt_success {0 /@}
+set cmd "rip "
+set bash_completion_pkg $::env(BASH_COMPLETION_PKG)
+
+proc line_count {str} {
+    regexp -all \n $str
+}
+
+# start bash with no startup files for clean env
+spawn env INPUTRC=/dev/null {PS1=$? /@} bash --norc --noprofile
+expect $prompt_success
+# set some readline variables for consistent completion output
+send "bind 'set show-all-if-ambiguous on'\r"
+expect $prompt_success
+send "bind 'set bell-style none'\r"
+expect $prompt_success
+send "bind 'set completion-query-items -1'\r"
+expect $prompt_success
+send "bind 'set page-completions off'\r"
+expect $prompt_success
+send "bind 'set completion-display-width 0'\r"
+expect $prompt_success
+
+# Source bash-completion's basic script which should load rip's completion (when first tab is pressed)
+send "source $bash_completion_pkg/etc/profile.d/bash_completion.sh\r"
+expect $prompt_success
+
+# Enter temporary folder to avoid listing files if completion is not loaded properly
+set tmp_dir [exec "mktemp" "-d"]
+send "cd $tmp_dir\r"
+expect $prompt_success
+
+# run the completion
+send "$cmd\t"
+expect -re "^$cmd\r\n(.*)\r\n$prompt_success$cmd" {
+    puts "Completions:\n$expect_out(1,string)\n"
+    set completion_count [line_count $expect_out(1,string)]
+    puts "Found $completion_count completions, expecting at least 10"
+    if {$completion_count > 10} {
+        exit 0
+    }
+}
+
+puts "Failed to generate completions"
+
+exit 1