class ActionCable::Channel::TestCase

Superclass for Action Cable channel functional tests.

Basic example

Functional tests are written as follows: 1. First, one uses the subscribe method to simulate subscription creation. 2. Then, one asserts whether the current state is as expected. “State” can be anything: transmitted messages, subscribed streams, etc.

For example:

class ChatChannelTest < ActionCable::Channel::TestCase
  def test_subscribed_with_room_number
    # Simulate a subscription creation
    subscribe room_number: 1

    # Asserts that the subscription was successfully created
    assert subscription.confirmed?

    # Asserts that the channel subscribes connection to a stream
    assert_has_stream "chat_1"

    # Asserts that the channel subscribes connection to a specific
    # stream created for a model
    assert_has_stream_for Room.find(1)
  end

  def test_does_not_stream_with_incorrect_room_number
    subscribe room_number: -1

    # Asserts that not streams was started
    assert_no_streams
  end

  def test_does_not_subscribe_without_room_number
    subscribe

    # Asserts that the subscription was rejected
    assert subscription.rejected?
  end
end

You can also perform actions: def test_perform_speak subscribe room_number: 1

  perform :speak, message: "Hello, Rails!"

  assert_equal "Hello, Rails!", transmissions.last["text"]
end

Special methods

ActionCable::Channel::TestCase will also automatically provide the following instance methods for use in the tests:

connection

An ActionCable::Channel::ConnectionStub, representing the current HTTP connection.

subscription

An instance of the current channel, created when you call subscribe.

transmissions

A list of all messages that have been transmitted into the channel.

Channel is automatically inferred

ActionCable::Channel::TestCase will automatically infer the channel under test from the test class name. If the channel cannot be inferred from the test class name, you can explicitly set it with tests.

class SpecialEdgeCaseChannelTest < ActionCable::Channel::TestCase
  tests SpecialChannel
end

Specifying connection identifiers

You need to set up your connection manually to provide values for the identifiers. To do this just use:

stub_connection(user: users(:john))

Testing broadcasting

ActionCable::Channel::TestCase enhances ActionCable::TestHelper assertions (e.g. assert_broadcasts) to handle broadcasting to models:

# in your channel
def speak(data)
  broadcast_to room, text: data["message"]
end

def test_speak
  subscribe room_id: rooms(:chat).id

  assert_broadcast_on(rooms(:chat), text: "Hello, Rails!") do
    perform :speak, message: "Hello, Rails!"
  end
end