Improve flaky Broadcast tests

First, don't render HTML with the `<turbo-stream-source>` element.
Instead, append the element when clicking a `<button>`.

Next, remove all waiting from Capybara tests, and rely on default
values.

Author: seanpdoyle

.github/workflows/ci.yml

@@ -21,6 +21,7 @@ jobs:
 
     env:
       RAILS_VERSION: "${{ matrix.rails-version }}"
+      VERBOSE: true
 
     name: ${{ format('Tests (Ruby {0}, Rails {1})', matrix.ruby-version, matrix.rails-version) }}
     runs-on: ubuntu-latest

test/dummy/app/views/application/_template_button.html.erb

@@ -0,0 +1,14 @@
+<button type="button">
+  <%= content %>
+
+  <script>
+    document.currentScript.parentElement.addEventListener("click", ({ currentTarget }) => {
+      for (const { content } of currentTarget.querySelectorAll("template")) {
+        currentTarget.parentElement.insertBefore(content, currentTarget)
+      }
+      currentTarget.remove()
+    })
+  </script>
+
+  <template><%= yield %></template>
+</button>

test/dummy/app/views/messages/echo.html.erb

@@ -1,5 +1,8 @@
 <h1>Echo Messages</h1>
 
-<%= turbo_stream_from "messages", channel: EchoChannel, data: {message: "Hello, world!"} %>
+<%= render "template_button", content: "Start listening for broadcasts" do %>
+  <%= turbo_stream_from "messages", channel: EchoChannel, data: {message: "Hello, world!"} %>
+<% end %>
+
 <div id="messages">
 </div>

test/dummy/app/views/messages/index.html.erb

@@ -1,9 +1,8 @@
 <h1>Messages</h1>
 
-<span id="message-count">
-  <%= @messages.count %> messages sent
-</span>
+<%= render "template_button", content: "Start listening for broadcasts" do %>
+  <%= turbo_stream_from "messages" %>
+<% end %>
 
-<%= turbo_stream_from "messages" %>
 <div id="messages">
 </div>

test/dummy/app/views/users/profiles/index.html.erb

@@ -1,4 +1,7 @@
 <h1>Users::Profiles</h1>
 
-<%= turbo_stream_from "users_profiles" %>
+<%= render "template_button", content: "Start listening for broadcasts" do %>
+  <%= turbo_stream_from "users_profiles" %>
+<% end %>
+
 <div id="users_profiles"></div>

test/dummy/config/cable.yml

@@ -2,7 +2,7 @@ development:
   adapter: async
 
 test:
-  adapter: async
+  adapter: inline
 
 production:
   adapter: redis

test/system/broadcasts_test.rb

@@ -1,69 +1,56 @@
 require "application_system_test_case"
 
 class BroadcastsTest < ApplicationSystemTestCase
-  include ActionCable::TestHelper
-
   test "Message broadcasts Turbo Streams" do
     visit messages_path
-    wait_for_subscriber
+    subscribe_to_broadcasts
 
-    assert_text "Messages"
-    assert_broadcasts_text "Message 1" do |text|
-      Message.create(content: text).broadcast_append_to(:messages)
+    assert_broadcasts_text "Message 1", to: :messages do |text, target|
+      Message.create(content: text).broadcast_append_to(target)
     end
   end
 
-  test "New messages update the message count with html" do
+  test "Message broadcasts with html: render option" do
     visit messages_path
-    wait_for_subscriber
-
-    assert_text "Messages"
-    message = Message.create(content: "A new message")
+    subscribe_to_broadcasts
 
-    message.broadcast_update_to(:messages, target: "message-count",
-      html: "#{Message.count} messages sent")
-    assert_selector("#message-count", text: Message.count, wait: 10)
+    assert_broadcasts_text "Hello, with html: option", to: :messages do |text, target|
+      Message.create(content: "Ignored").broadcast_append_to(target, html: text)
+    end
   end
 
   test "Users::Profile broadcasts Turbo Streams" do
     visit users_profiles_path
-    wait_for_subscriber
+    subscribe_to_broadcasts
 
-    assert_text "Users::Profiles"
-    assert_broadcasts_text "Profile 1" do |text|
-      Users::Profile.new(id: 1, name: text).broadcast_append_to(:users_profiles)
+    assert_broadcasts_text "Profile 1", to: :users_profiles do |text, target|
+      Users::Profile.new(id: 1, name: text).broadcast_append_to(target)
     end
   end
 
   test "passing extra parameters to channel" do
     visit echo_messages_path
-    wait_for_subscriber
 
-    assert_text "Hello, world!", wait: 100
+    assert_broadcasts_text "Hello, world!", to: :messages do
+      subscribe_to_broadcasts
+    end
   end
 
   private
 
-  def assert_broadcasts_text(text, wait: 5, &block)
-    assert_no_text text
-    perform_enqueued_jobs { block.call(text) }
-    assert_text text, wait: wait
+  def subscribe_to_broadcasts
+    click_on "Start listening for broadcasts"
+
+    assert_no_button "Start listening for broadcasts"
   end
 
-  def wait_for_subscriber(timeout: 10)
-    time = Time.now
-    loop do
-      subscriber_map = pubsub_adapter.instance_variable_get(:@subscriber_map)
-      if subscriber_map.is_a?(ActionCable::SubscriptionAdapter::SubscriberMap)
-        subscribers = subscriber_map.instance_variable_get(:@subscribers)
-        sync = subscriber_map.instance_variable_get(:@sync)
-        sync.synchronize do
-          return unless subscribers.empty?
-        end
-      end
-      assert_operator(Time.now - time, :<, timeout, "subscriber waiting timed out")
-      sleep 0.1
+  def assert_broadcasts_text(text, to:, wait: 10, &block)
+    using_wait_time wait do
+      assert_no_text text
+
+      [text, to].yield_self(&block)
+
+      assert_text text
     end
   end
-
 end