test: add bats unit tests for common.sh and config.sh

23 bats tests covering the pure logic in installer/lib/common.sh
(command_exists, require_command, info/warn/error, enable_color,
require_root, log) and installer/lib/config.sh (parse_args, load_config,
validate_config, check_config). Makefile adds a 'bats' target; 'test'
now runs lint + bats (VM integration tests remain under test-install).

1 files changed, 88 insertions, 0 deletions

diff --git a/tests/unit/test_common.bats b/tests/unit/test_common.bats
new file mode 100644
index 0000000..6b9c18f
--- /dev/null
+++ b/tests/unit/test_common.bats
@@ -0,0 +1,88 @@
+#!/usr/bin/env bats
+# Unit tests for installer/lib/common.sh
+
+setup() {
+    # shellcheck disable=SC1091
+    source "${BATS_TEST_DIRNAME}/../../installer/lib/common.sh"
+}
+
+@test "command_exists returns 0 for an existing command" {
+    run command_exists bash
+    [ "$status" -eq 0 ]
+}
+
+@test "command_exists returns 1 for a missing command" {
+    run command_exists this_does_not_exist_xyz_42
+    [ "$status" -eq 1 ]
+}
+
+@test "require_command succeeds for an existing command" {
+    run require_command bash
+    [ "$status" -eq 0 ]
+}
+
+@test "require_command fails and reports missing command" {
+    run require_command this_does_not_exist_xyz_42
+    [ "$status" -eq 1 ]
+    [[ "$output" == *"Required command not found"* ]]
+    [[ "$output" == *"this_does_not_exist_xyz_42"* ]]
+}
+
+@test "enable_color populates color variables" {
+    [ -z "$RED" ]
+    [ -z "$GREEN" ]
+    [ -z "$NC" ]
+    enable_color
+    [ -n "$RED" ]
+    [ -n "$GREEN" ]
+    [ -n "$YELLOW" ]
+    [ -n "$BLUE" ]
+    [ -n "$BOLD" ]
+    [ -n "$NC" ]
+}
+
+@test "info prints [INFO] prefix and message" {
+    run info "hello world"
+    [ "$status" -eq 0 ]
+    [[ "$output" == *"[INFO]"* ]]
+    [[ "$output" == *"hello world"* ]]
+}
+
+@test "warn prints [WARN] prefix and message" {
+    run warn "heads up"
+    [ "$status" -eq 0 ]
+    [[ "$output" == *"[WARN]"* ]]
+    [[ "$output" == *"heads up"* ]]
+}
+
+@test "error prints [ERROR] and exits with status 1" {
+    run error "something broke"
+    [ "$status" -eq 1 ]
+    [[ "$output" == *"[ERROR]"* ]]
+    [[ "$output" == *"something broke"* ]]
+}
+
+@test "require_root fails for non-root user" {
+    [ "$EUID" -ne 0 ] || skip "running as root"
+    run require_root
+    [ "$status" -eq 1 ]
+    [[ "$output" == *"must be run as root"* ]]
+}
+
+@test "log writes timestamped line when LOG_FILE set" {
+    local tmp
+    tmp=$(mktemp)
+    LOG_FILE="$tmp" log "test entry"
+    run cat "$tmp"
+    [ "$status" -eq 0 ]
+    [[ "$output" == *"test entry"* ]]
+    [[ "$output" =~ \[[0-9]{4}-[0-9]{2}-[0-9]{2} ]]
+    rm -f "$tmp"
+}
+
+@test "log is a no-op when LOG_FILE unset" {
+    unset LOG_FILE
+    run log "should not crash"
+    [ "$status" -eq 0 ]
+    [ -z "$output" ]
+}