1 files changed, 19 insertions, 0 deletions
diff --git a/actioncable/test/subscription_adapter/subscriber_map_test.rb b/actioncable/test/subscription_adapter/subscriber_map_test.rb
new file mode 100644
index 0000000000..ed81099cbc
--- /dev/null
+++ b/actioncable/test/subscription_adapter/subscriber_map_test.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+class SubscriberMapTest < ActionCable::TestCase
+  test "broadcast should not change subscribers" do
+    setup_subscription_map
+    origin = @subscription_map.instance_variable_get(:@subscribers).dup
+
+    @subscription_map.broadcast("not_exist_channel", "")
+
+    assert_equal origin, @subscription_map.instance_variable_get(:@subscribers)
+  end
+
+  private
+    def setup_subscription_map
+      @subscription_map = ActionCable::SubscriptionAdapter::SubscriberMap.new
+    end
+end