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have_broadcasted_to matcher

The have_broadcasted_to (also aliased as broadcast_to) matcher is used to check if a message has been broadcasted to a given stream.

Background​

Given action cable testing is available.

Checking stream name​

Given a file named "spec/models/broadcaster_spec.rb" with:

require "rails_helper"

RSpec.describe "broadcasting" do
  it "matches with stream name" do
    expect {
      ActionCable.server.broadcast(
        "notifications", { text: "Hello!" }
      )
    }.to have_broadcasted_to("notifications")
  end
end

When I run rspec spec/models/broadcaster_spec.rb

Then the examples should all pass.

Checking passed message to stream​

Given a file named "spec/models/broadcaster_spec.rb" with:

require "rails_helper"

RSpec.describe "broadcasting" do
  it "matches with message" do
    expect {
      ActionCable.server.broadcast(
        "notifications", { text: "Hello!" }
      )
    }.to have_broadcasted_to("notifications").with(text: 'Hello!')
  end
end

When I run rspec spec/models/broadcaster_spec.rb

Then the examples should all pass.

Checking that message passed to stream matches​

Given a file named "spec/models/broadcaster_spec.rb" with:

require "rails_helper"

RSpec.describe "broadcasting" do
  it "matches with message" do
    expect {
      ActionCable.server.broadcast(
        "notifications", { text: 'Hello!', user_id: 12 }
      )
    }.to have_broadcasted_to("notifications").with(a_hash_including(text: 'Hello!'))
  end
end

When I run rspec spec/models/broadcaster_spec.rb

Then the examples should all pass.

Checking passed message with block​

Given a file named "spec/models/broadcaster_spec.rb" with:

require "rails_helper"

RSpec.describe "broadcasting" do
  it "matches with message" do
    expect {
      ActionCable.server.broadcast(
        "notifications", { text: 'Hello!', user_id: 12 }
      )
    }.to have_broadcasted_to("notifications").with { |data|
      expect(data['user_id']).to eq 12
    }
  end
end

When I run rspec spec/models/broadcaster_spec.rb

Then the examples should all pass.

Using alias method​

Given a file named "spec/models/broadcaster_spec.rb" with:

require "rails_helper"

RSpec.describe "broadcasting" do
  it "matches with stream name" do
    expect {
      ActionCable.server.broadcast(
        "notifications", { text: 'Hello!' }
      )
    }.to broadcast_to("notifications")
  end
end

When I run rspec spec/models/broadcaster_spec.rb

Then the examples should all pass.

Checking broadcast to a record​

Given a file named "spec/channels/chat_channel_spec.rb" with:

require "rails_helper"

RSpec.describe ChatChannel, type: :channel do
  it "matches with stream name" do
    user = User.new(42)

    expect {
      ChatChannel.broadcast_to(user, text: 'Hi')
    }.to have_broadcasted_to(user)
  end
end

And a file named "app/models/user.rb" with:

class User < Struct.new(:name)
  def to_gid_param
    name
  end
end

When I run rspec spec/channels/chat_channel_spec.rb

Then the example should pass.

Checking broadcast to a record in non-channel spec​

Given a file named "spec/models/broadcaster_spec.rb" with:

require "rails_helper"

RSpec.describe "broadcasting" do
  it "matches with stream name" do
    user = User.new(42)

    expect {
      ChatChannel.broadcast_to(user, text: 'Hi')
    }.to broadcast_to(ChatChannel.broadcasting_for(user))
  end
end

And a file named "app/models/user.rb" with:

class User < Struct.new(:name)
  def to_gid_param
    name
  end
end

When I run rspec spec/models/broadcaster_spec.rb

Then the example should pass.