diff --git a/common/mux/client_test.go b/common/mux/client_test.go
new file mode 100644
index 000000000..8c86af811
--- /dev/null
+++ b/common/mux/client_test.go
@@ -0,0 +1,21 @@
+package mux_test
+
+import (
+	"testing"
+
+	"v2ray.com/core/common/errors"
+	"v2ray.com/core/common/mux"
+)
+
+func TestIncrementalPickerFailure(t *testing.T) {
+	picker := mux.IncrementalWorkerPicker{
+		New: func() (*mux.ClientWorker, error) {
+			return nil, errors.New("test")
+		},
+	}
+
+	_, err := picker.PickAvailable()
+	if err == nil {
+		t.Error("expected error, but nil")
+	}
+}