diff --git a/client.go b/client.go
index 71bc154..b531bb8 100644
--- a/client.go
+++ b/client.go
@@ -341,6 +341,9 @@ func (c *Client) Enqueue(task *Task, opts ...Option) (*TaskInfo, error) {
 //
 // The first argument context applies to the enqueue operation. To specify task timeout and deadline, use Timeout and Deadline option instead.
 func (c *Client) EnqueueContext(ctx context.Context, task *Task, opts ...Option) (*TaskInfo, error) {
+	if task == nil {
+		return nil, fmt.Errorf("task cannot be nil")
+	}
 	if strings.TrimSpace(task.Type()) == "" {
 		return nil, fmt.Errorf("task typename cannot be empty")
 	}
diff --git a/client_test.go b/client_test.go
index d305d76..2d4330e 100644
--- a/client_test.go
+++ b/client_test.go
@@ -857,6 +857,11 @@ func TestClientEnqueueError(t *testing.T) {
 		task *Task
 		opts []Option
 	}{
+		{
+			desc: "With nil task",
+			task: nil,
+			opts: []Option{},
+		},
 		{
 			desc: "With empty queue name",
 			task: task,
diff --git a/internal/testbroker/testbroker.go b/internal/testbroker/testbroker.go
index ce35866..5d228d5 100644
--- a/internal/testbroker/testbroker.go
+++ b/internal/testbroker/testbroker.go
@@ -234,3 +234,57 @@ func (tb *TestBroker) Close() error {
 	}
 	return tb.real.Close()
 }
+
+func (tb *TestBroker) AddToGroup(ctx context.Context, msg *base.TaskMessage, gname string) error {
+	tb.mu.Lock()
+	defer tb.mu.Unlock()
+	if tb.sleeping {
+		return errRedisDown
+	}
+	return tb.real.AddToGroup(ctx, msg, gname)
+}
+
+func (tb *TestBroker) AddToGroupUnique(ctx context.Context, msg *base.TaskMessage, gname string, ttl time.Duration) error {
+	tb.mu.Lock()
+	defer tb.mu.Unlock()
+	if tb.sleeping {
+		return errRedisDown
+	}
+	return tb.real.AddToGroupUnique(ctx, msg, gname, ttl)
+}
+
+func (tb *TestBroker) ListGroups(qname string) ([]string, error) {
+	tb.mu.Lock()
+	defer tb.mu.Unlock()
+	if tb.sleeping {
+		return nil, errRedisDown
+	}
+	return tb.real.ListGroups(qname)
+}
+
+func (tb *TestBroker) AggregationCheck(qname, gname string, t time.Time, gracePeriod, maxDelay time.Duration, maxSize int) (aggregationSetID string, err error) {
+	tb.mu.Lock()
+	defer tb.mu.Unlock()
+	if tb.sleeping {
+		return "", errRedisDown
+	}
+	return tb.real.AggregationCheck(qname, gname, t, gracePeriod, maxDelay, maxSize)
+}
+
+func (tb *TestBroker) ReadAggregationSet(qname, gname, aggregationSetID string) ([]*base.TaskMessage, time.Time, error) {
+	tb.mu.Lock()
+	defer tb.mu.Unlock()
+	if tb.sleeping {
+		return nil, time.Time{}, errRedisDown
+	}
+	return tb.real.ReadAggregationSet(qname, gname, aggregationSetID)
+}
+
+func (tb *TestBroker) DeleteAggregationSet(ctx context.Context, qname, gname, aggregationSetID string) error {
+	tb.mu.Lock()
+	defer tb.mu.Unlock()
+	if tb.sleeping {
+		return errRedisDown
+	}
+	return tb.real.DeleteAggregationSet(ctx, qname, gname, aggregationSetID)
+}