fix: parse install flags consistently

.github/workflows/shellcheck.yml

@@ -20,4 +20,7 @@ jobs:
 
       - name: Run ShellCheck on all shell scripts
         run: |
-          shellcheck pre-commit commit-msg pre-push post-checkout post-commit post-merge install.sh uninstall.sh
+          shellcheck pre-commit commit-msg pre-push post-checkout post-commit post-merge install.sh uninstall.sh test/install_test.sh
+
+      - name: Run install script regression tests
+        run: bash test/install_test.sh

README.md

@@ -76,6 +76,8 @@ See what's currently configured without changing anything:
 cd ~/.git-hooks && ./install.sh --check
 ```
 
+`--check` can be combined with other flags like `--template` to inspect what would be used without changing your git config.
+
 ### Uninstall
 
 ```bash

install.sh

@@ -7,8 +7,41 @@
 set -euo pipefail
 
 hook_dir="$(cd "$(dirname "$0")" && pwd)"
+use_template=false
+check_only=false
 
-if [ "${1:-}" = "--check" ]; then
+usage() {
+	cat <<EOF
+Usage: ./install.sh [--template] [--check] [--help]
+
+Options:
+  --template  Use init.templateDir instead of core.hooksPath
+  --check     Show current hooks configuration without changing anything
+  --help      Show this help text
+EOF
+}
+
+for arg in "$@"; do
+	case "$arg" in
+		--template)
+			use_template=true
+			;;
+		--check)
+			check_only=true
+			;;
+		--help|-h)
+			usage
+			exit 0
+			;;
+		*)
+			echo "Unknown option: $arg" >&2
+			usage >&2
+			exit 1
+			;;
+	esac
+done
+
+if [ "$check_only" = true ]; then
 	hooks_path=$(git config --global --get core.hooksPath 2>/dev/null || true)
 	template_dir=$(git config --global --get init.templateDir 2>/dev/null || true)
 	if [ -n "$hooks_path" ]; then
@@ -33,7 +66,7 @@ if [ "${1:-}" = "--check" ]; then
 	exit 0
 fi
 
-if [ "${1:-}" = "--template" ]; then
+if [ "$use_template" = true ]; then
 	git config --global init.templateDir "$hook_dir"
 	echo "Installed: init.templateDir set to $hook_dir"
 	echo "New repos created with git init/clone will copy these hooks."

test/install_test.sh

@@ -0,0 +1,67 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+repo_root="$(cd "$(dirname "$0")/.." && pwd)"
+install_script="$repo_root/install.sh"
+tmpdir="$(mktemp -d)"
+trap 'rm -rf "$tmpdir"' EXIT
+
+export HOME="$tmpdir/home"
+mkdir -p "$HOME"
+
+global_config="$HOME/.gitconfig"
+
+run() {
+	local expected_status="$1"
+	shift
+	set +e
+	output=$(GIT_CONFIG_GLOBAL="$global_config" "$@" 2>&1)
+	status=$?
+	set -e
+	if [ "$status" -ne "$expected_status" ]; then
+		echo "expected exit $expected_status, got $status" >&2
+		echo "$output" >&2
+		exit 1
+	fi
+	printf '%s' "$output"
+}
+
+assert_contains() {
+	local haystack="$1"
+	local needle="$2"
+	if ! printf '%s' "$haystack" | grep -Fq "$needle"; then
+		echo "expected output to contain: $needle" >&2
+		echo "$haystack" >&2
+		exit 1
+	fi
+}
+
+assert_unset() {
+	local key="$1"
+	if GIT_CONFIG_GLOBAL="$global_config" git config --global --get "$key" >/dev/null 2>&1; then
+		echo "expected $key to be unset" >&2
+		exit 1
+	fi
+}
+
+output=$(run 0 bash "$install_script" --check)
+assert_contains "$output" "No global hooks configuration found."
+
+output=$(run 0 bash "$install_script" --template --check)
+assert_contains "$output" "No global hooks configuration found."
+assert_unset core.hooksPath
+assert_unset init.templateDir
+
+output=$(run 0 bash "$install_script" --template)
+assert_contains "$output" "Installed: init.templateDir set to $repo_root"
+template_dir=$(GIT_CONFIG_GLOBAL="$global_config" git config --global --get init.templateDir)
+[ "$template_dir" = "$repo_root" ]
+
+output=$(run 1 bash "$install_script" --bogus)
+assert_contains "$output" "Unknown option: --bogus"
+
+output=$(run 0 bash "$install_script" --help)
+assert_contains "$output" "Usage: ./install.sh"
+
+echo "install.sh regression tests passed"