diff --git a/x/inspector/inspector_test.go b/x/inspector/inspector_test.go
new file mode 100644
index 0000000..6ac11a1
--- /dev/null
+++ b/x/inspector/inspector_test.go
@@ -0,0 +1,103 @@
+package inspector
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"code.tczkiot.com/wlw/taskq"
+	"github.com/hibiken/asynq"
+	_ "github.com/mattn/go-sqlite3"
+	"github.com/redis/go-redis/v9"
+)
+
+func TestNewDefaultsAndName(t *testing.T) {
+	ins := New(Options{})
+	if ins == nil {
+		t.Fatalf("New returned nil")
+	}
+	if ins.opts.Interval <= 0 {
+		t.Fatalf("expected default Interval > 0")
+	}
+	if ins.opts.DBPath == "" {
+		t.Fatalf("expected default DBPath set")
+	}
+	if ins.Name() != "inspector" {
+		t.Fatalf("unexpected Name: %s", ins.Name())
+	}
+}
+
+func TestConvertTaskHelpers(t *testing.T) {
+	// ensure convertTaskInfo/convertTaskList are callable
+	_ = convertTaskInfo(&asynq.TaskInfo{})
+	_ = convertTaskList([]*asynq.TaskInfo{})
+}
+
+func TestGetQueueInfoWhenNotStarted(t *testing.T) {
+	ins := New(Options{})
+	if _, err := ins.GetQueueInfo("default"); err == nil {
+		t.Fatalf("expected error when inspector not started")
+	}
+}
+
+func TestListActiveTasksWhenNotStarted(t *testing.T) {
+	ins := New(Options{})
+	if _, err := ins.ListActiveTasks("default", 10, 0); err == nil {
+		t.Fatalf("expected error when inspector not started")
+	}
+}
+
+func TestSaveMetrics_NoDB(t *testing.T) {
+	ins := New(Options{})
+	// db is nil by default; saveMetrics should return nil (no-op)
+	s := Stats{Queue: "q", Timestamp: time.Now().Unix()}
+	if err := ins.saveMetrics(s); err != nil {
+		t.Fatalf("saveMetrics returned error with nil db: %v", err)
+	}
+}
+
+// helper: create redis client for tests
+func makeTestRedis(t *testing.T) redis.UniversalClient {
+	rdb := redis.NewClient(&redis.Options{Addr: "localhost:6379", DB: 15})
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+	if err := rdb.Ping(ctx).Err(); err != nil {
+		t.Skipf("redis not available: %v", err)
+	}
+	// flush test DB
+	if err := rdb.FlushDB(context.Background()).Err(); err != nil {
+		t.Fatalf("failed to flush redis: %v", err)
+	}
+	return rdb
+}
+
+func TestPluginLifecycleWithServlet(t *testing.T) {
+	rdb := makeTestRedis(t)
+	// create plugin
+	ins := New(Options{DBPath: ":memory:", Interval: time.Second})
+
+	// wire into a fresh servlet as default to use package-level helpers
+	s := taskq.NewServlet()
+	taskq.SetDefault(s)
+
+	cfg := taskq.Config{Redis: rdb, Tasks: []*taskq.Task{}, Plugins: []taskq.Plugin{ins}}
+	if err := taskq.Configure(cfg); err != nil {
+		t.Fatalf("Configure failed: %v", err)
+	}
+
+	if err := taskq.Init(context.Background()); err != nil {
+		t.Fatalf("Init failed: %v", err)
+	}
+
+	if err := taskq.Start(context.Background()); err != nil {
+		t.Fatalf("Start failed: %v", err)
+	}
+
+	// request stop
+	taskq.Stop()
+	// wait for plugins and internal goroutines to shutdown
+	time.Sleep(500 * time.Millisecond)
+
+	// close redis
+	rdb.Close()
+}
diff --git a/x/metrics/metrics_test.go b/x/metrics/metrics_test.go
new file mode 100644
index 0000000..212f09d
--- /dev/null
+++ b/x/metrics/metrics_test.go
@@ -0,0 +1,68 @@
+package metrics
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"code.tczkiot.com/wlw/taskq"
+	"github.com/redis/go-redis/v9"
+)
+
+func TestNewDefaultsAndName(t *testing.T) {
+	m := New(Options{})
+	if m == nil {
+		t.Fatalf("New returned nil")
+	}
+	if m.opts.Namespace == "" {
+		t.Fatalf("expected default Namespace")
+	}
+	if m.Name() != "metrics" {
+		t.Fatalf("unexpected Name: %s", m.Name())
+	}
+}
+
+func TestCollectNoInspectorNoQueues(t *testing.T) {
+	m := New(Options{Interval: time.Millisecond})
+	// ensure collect() is safe to call when inspector or queues are nil
+	m.collect()
+}
+
+func makeTestRedis(t *testing.T) redis.UniversalClient {
+	rdb := redis.NewClient(&redis.Options{Addr: "localhost:6379", DB: 15})
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+	if err := rdb.Ping(ctx).Err(); err != nil {
+		t.Skipf("redis not available: %v", err)
+	}
+	if err := rdb.FlushDB(context.Background()).Err(); err != nil {
+		t.Fatalf("failed to flush redis: %v", err)
+	}
+	return rdb
+}
+
+func TestMetricsLifecycleWithServlet(t *testing.T) {
+	rdb := makeTestRedis(t)
+	m := New(Options{Interval: time.Second})
+
+	// register plugin via default servlet
+	s := taskq.NewServlet()
+	taskq.SetDefault(s)
+
+	cfg := taskq.Config{Redis: rdb, Tasks: []*taskq.Task{}, Plugins: []taskq.Plugin{m}}
+	if err := taskq.Configure(cfg); err != nil {
+		t.Fatalf("Configure failed: %v", err)
+	}
+
+	if err := taskq.Init(context.Background()); err != nil {
+		t.Fatalf("Init failed: %v", err)
+	}
+
+	if err := taskq.Start(context.Background()); err != nil {
+		t.Fatalf("Start failed: %v", err)
+	}
+
+	taskq.Stop()
+	time.Sleep(500 * time.Millisecond)
+	rdb.Close()
+}
diff --git a/x/monitor/monitor_test.go b/x/monitor/monitor_test.go
new file mode 100644
index 0000000..59e2c42
--- /dev/null
+++ b/x/monitor/monitor_test.go
@@ -0,0 +1,48 @@
+package monitor
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"code.tczkiot.com/wlw/taskq/x/inspector"
+)
+
+func TestNewValidatesOptions(t *testing.T) {
+	_, err := New(Options{})
+	if err == nil {
+		t.Fatalf("expected error when options missing")
+	}
+
+	// valid case
+	ins := &inspector.Inspector{}
+	m, err := New(Options{Inspector: ins, Queues: map[string]int{"default": 1}})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if m.RootPath() != "/monitor" {
+		t.Fatalf("unexpected root path: %s", m.RootPath())
+	}
+}
+
+func TestHandleIndexServesUI(t *testing.T) {
+	ins := &inspector.Inspector{}
+	m, err := New(Options{Inspector: ins, Queues: map[string]int{"default": 1}, RootPath: "/my"})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	req := httptest.NewRequest(http.MethodGet, "/my/", nil)
+	w := httptest.NewRecorder()
+	m.ServeHTTP(w, req)
+
+	resp := w.Result()
+	if resp.StatusCode != http.StatusOK {
+		t.Fatalf("expected 200 OK, got %d", resp.StatusCode)
+	}
+	// body should contain the root path replacement
+	body := w.Body.String()
+	if body == "" {
+		t.Fatalf("expected non-empty index body")
+	}
+}