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Provides helper methods for testing Action Cable broadcasting

Methods
A
Instance Public methods
assert_broadcast_on(stream, data)

Asserts that the specified message has been sent to the stream.

def test_assert_transmitted_message
  ActionCable.server.broadcast 'messages', text: 'hello'
  assert_broadcast_on('messages', text: 'hello')
end

If a block is passed, that block should cause a message with the specified data to be sent.

def test_assert_broadcast_on_again
  assert_broadcast_on('messages', text: 'hello') do
    ActionCable.server.broadcast 'messages', text: 'hello'
  end
end
# File actioncable/lib/action_cable/test_helper.rb, line 97
def assert_broadcast_on(stream, data)
  # Encode to JSON and back–we want to use this value to compare
  # with decoded JSON.
  # Comparing JSON strings doesn't work due to the order if the keys.
  serialized_msg =
    ActiveSupport::JSON.decode(ActiveSupport::JSON.encode(data))

  new_messages = broadcasts(stream)
  if block_given?
    old_messages = new_messages
    clear_messages(stream)

    yield
    new_messages = broadcasts(stream)
    clear_messages(stream)

    # Restore all sent messages
    (old_messages + new_messages).each { |m| pubsub_adapter.broadcast(stream, m) }
  end

  message = new_messages.find { |msg| ActiveSupport::JSON.decode(msg) == serialized_msg }

  assert message, "No messages sent with #{data} to #{stream}"
end
assert_broadcasts(stream, number)

Asserts that the number of broadcasted messages to the stream matches the given number.

def test_broadcasts
  assert_broadcasts 'messages', 0
  ActionCable.server.broadcast 'messages', { text: 'hello' }
  assert_broadcasts 'messages', 1
  ActionCable.server.broadcast 'messages', { text: 'world' }
  assert_broadcasts 'messages', 2
end

If a block is passed, that block should cause the specified number of messages to be broadcasted.

def test_broadcasts_again
  assert_broadcasts('messages', 1) do
    ActionCable.server.broadcast 'messages', { text: 'hello' }
  end

  assert_broadcasts('messages', 2) do
    ActionCable.server.broadcast 'messages', { text: 'hi' }
    ActionCable.server.broadcast 'messages', { text: 'how are you?' }
  end
end
# File actioncable/lib/action_cable/test_helper.rb, line 45
def assert_broadcasts(stream, number)
  if block_given?
    original_count = broadcasts_size(stream)
    yield
    new_count = broadcasts_size(stream)
    actual_count = new_count - original_count
  else
    actual_count = broadcasts_size(stream)
  end

  assert_equal number, actual_count, "#{number} broadcasts to #{stream} expected, but #{actual_count} were sent"
end
assert_no_broadcasts(stream, &block)

Asserts that no messages have been sent to the stream.

def test_no_broadcasts
  assert_no_broadcasts 'messages'
  ActionCable.server.broadcast 'messages', { text: 'hi' }
  assert_broadcasts 'messages', 1
end

If a block is passed, that block should not cause any message to be sent.

def test_broadcasts_again
  assert_no_broadcasts 'messages' do
    # No job messages should be sent from this block
  end
end

Note: This assertion is simply a shortcut for:

assert_broadcasts 'messages', 0, &block
# File actioncable/lib/action_cable/test_helper.rb, line 78
def assert_no_broadcasts(stream, &block)
  assert_broadcasts stream, 0, &block
end