Stub WebSocket transport for testing event handlers without Socket Mode.

Use this to simulate Slack sending events to your bot—perfect for testing handlers in isolation without depending on live Slack connections.

Configuration

Set this as your transport in test config:

# config/test.exs
config :my_app, MyApp.SlackBot,
  transport: SlackBot.TestTransport,
  http_client: SlackBot.TestHTTP

Usage in Tests

The test transport exposes functions to simulate Socket Mode events:

Emit events to trigger handlers

test "handles app_mention events" do
  {:ok, _pid} = start_supervised(MyApp.SlackBot)

  # Get the transport PID
  transport = get_transport_pid(MyApp.SlackBot)

  # Simulate Slack sending an app_mention
  SlackBot.TestTransport.emit(transport, "app_mention", %{
    "type" => "app_mention",
    "channel" => "C123",
    "user" => "U456",
    "text" => "<@BOTID> help",
    "ts" => "1234567890.123456"
  })

  # Assert your handler's side effects
  assert_receive {:message_sent, "C123", _text}
end

Simulate disconnects

test "handles disconnect gracefully" do
  transport = get_transport_pid(MyApp.SlackBot)

  SlackBot.TestTransport.disconnect(transport, %{
    "reason" => "warning",
    "debug_info" => %{"host" => "applink.example"}
  })

  # Assert reconnection behavior
  assert_receive {:connection_state, :reconnecting}
end

Getting the Transport PID

Helper to extract transport PID in tests:

defp get_transport_pid(bot) do
  config = SlackBot.config(bot)
  manager = Module.concat(config.instance_name, ConnectionManager)

  # Implementation depends on your test setup
  # You may need to add a helper to ConnectionManager
  :sys.get_state(manager).transport_pid
end

Or use the :notify option:

test "emits event" do
  test_pid = self()

  config = %SlackBot.Config{
    transport: SlackBot.TestTransport,
    transport_opts: [notify: test_pid],
    # ...
  }

  start_supervised({SlackBot, config: config})

  assert_receive {:test_transport, transport_pid}

  SlackBot.TestTransport.emit(transport_pid, "message", %{...})
end

Complete Test Example

defmodule MyApp.SlackBotTest do
  use ExUnit.Case

  setup do
    start_supervised!(MyApp.SlackBot)
    transport = get_transport_pid(MyApp.SlackBot)
    {:ok, transport: transport}
  end

  test "responds to mentions", %{transport: transport} do
    SlackBot.TestTransport.emit(transport, "app_mention", %{
      "channel" => "C123",
      "user" => "U456",
      "text" => "<@BOT> ping"
    })

    # Assert response was sent
    assert_receive {:api_call, "chat.postMessage", %{"text" => "pong"}}
  end
end

API

• emit/4 - Simulate Slack sending an event
• disconnect/2 - Simulate connection loss

See Also

• SlackBot.TestHTTP - Stub HTTP client for API calls
• Example app: examples/basic_bot/