pool: add ConnectOption/WithDialer for per-call dialer override on Connect

pool.go

@@ -231,7 +231,22 @@ func (p *Pool) Close() {
 	}()
 }
 
-func (p *Pool) Connect(id string) error {
+// ConnectOption configures a single Connect call.
+type ConnectOption func(*connectOptions)
+
+type connectOptions struct {
+	dialer types.Dialer
+}
+
+// WithDialer returns a ConnectOption that overrides the pool dialer for this
+// connection only.
+func WithDialer(d types.Dialer) ConnectOption {
+	return func(o *connectOptions) {
+		o.dialer = d
+	}
+}
+
+func (p *Pool) Connect(id string, opts ...ConnectOption) error {
 	if p.logger != nil {
 		p.logger.Info("connecting", "peer", id)
 	}
@@ -258,8 +273,17 @@ func (p *Pool) Connect(id string) error {
 		return err
 	}
 
+	o := &connectOptions{}
+	for _, opt := range opts {
+		opt(o)
+	}
+	effectiveDialer := p.dialer
+	if o.dialer != nil {
+		effectiveDialer = o.dialer
+	}
+
 	cc := p.config.ConnectionConfig.Clone()
-	cc.Dialer = p.dialer
+	cc.Dialer = effectiveDialer
 
 	pool := PoolPlugin{
 		Inbox:            p.inbox,

pool_test.go

@@ -90,6 +90,51 @@ func TestPoolConnect(t *testing.T) {
 	})
 }
 
+func TestPoolConnectWithDialer(t *testing.T) {
+	t.Run("per-call dialer is used instead of pool dialer", func(t *testing.T) {
+		perCallUsed := false
+		perCallDialer := &honeybeetest.MockDialer{
+			DialContextFunc: func(ctx context.Context, url string, h http.Header) (types.Socket, *http.Response, error) {
+				perCallUsed = true
+				return honeybeetest.NewMockSocket(), nil, nil
+			},
+		}
+
+		// pool dialer should NOT be called
+		poolDialer := &honeybeetest.MockDialer{
+			DialContextFunc: func(context.Context, string, http.Header) (types.Socket, *http.Response, error) {
+				t.Error("pool dialer should not be called when per-call dialer is provided")
+				return nil, nil, fmt.Errorf("unexpected call")
+			},
+		}
+
+		cc := *transport.GetDefaultConnectionConfig()
+		cc.Dialer = poolDialer
+		pool, err := NewPool(context.Background(), &PoolConfig{
+			InboxBufferSize:  256,
+			EventsBufferSize: 10,
+			ConnectionConfig: cc,
+			WorkerConfig:     *GetDefaultWorkerConfig(),
+		}, nil)
+		assert.NoError(t, err)
+
+		err = pool.Connect("wss://test", WithDialer(perCallDialer))
+		assert.NoError(t, err)
+
+		honeybeetest.Eventually(t, func() bool {
+			select {
+			case e := <-pool.events:
+				return e.ID == "wss://test" && e.Kind == EventConnected
+			default:
+				return false
+			}
+		}, "expected connected event")
+
+		assert.True(t, perCallUsed, "per-call dialer was not used")
+		pool.Close()
+	})
+}
+
 func TestPoolClose(t *testing.T) {
 	t.Run("channels close after pool close", func(t *testing.T) {
 		pool, _ := NewPool(context.Background(), nil, nil)