Hello, everyone
I’ve faced with the issue of running worker with start_supervised! macro in ExUnit tests, but can’t figure out what is the actual problem is and how to fix it.
Before writing code for application, I’ve prepared specific package for my own needs so that it will be shared across other modules, that gonna be used later on. The code is quite simple (full source of this worker is available here):
defmodule Spotter.Worker do
@moduledoc """
Base worker module that works with AMQP.
"""
@doc """
Create a link to worker process. Used in supervisors.
"""
@callback start_link :: Supervisor.on_start
@doc """
Get queue status.
"""
@callback status :: {:ok, %{consumer_count: integer, message_count: integer, queue: String.t()}} | {:error, String.t()}
@doc false
defmacro __using__(opts) do
quote bind_quoted: [opts: opts] do
use GenServer
use Confex, Keyword.delete(opts, :connection)
require Logger
@connection Keyword.get(opts, :connection) || @module_config[:connection]
@channel_name String.to_atom("#{__MODULE__}.Channel")
unless @connection do
raise "You need to implement connection module and pass it in :connection option."
end
def start_link() do
GenServer.start_link(__MODULE__, %{config: config(), opts: []})
end
def start_link(opts) do
GenServer.start_link(__MODULE__, %{config: config(), opts: opts})
end
# Other implemented methods for worker class
# ...
defoverridable [configure: 2, validate_config!: 1]
end
end
end
Then, in application I written special module that defines extra functionality (sources here):
defmodule Matchmaking.AMQP.Worker do
@moduledoc """
Base module for implementing workers of Mathcmaking microservice
"""
@doc false
defmacro __using__(opts) do
quote bind_quoted: [opts: opts] do
use AMQP
use Spotter.Worker,
otp_app: :matchmaking,
connection: Matchmaking.AMQP.Connection,
queue: Keyword.get(opts, :queue, []),
exchange: Keyword.get(opts, :exchange, []),
qos: Keyword.get(opts, :qos, [])
unless opts[:queue] do
raise "You need to configure queue in #{__MODULE__} options."
end
unless opts[:queue][:name] do
raise "You need to configure queue[:name] in #{__MODULE__} options."
end
# Other implemented functions are skipped here
end
end
end
After is this module shares the implementation across other modules and each of them provide its own logic for something with processing incoming messages from RabbitMQ queues. It looks like this:
defmodule Matchmaking.Middleware.Worker do
@moduledoc false
@exchange_request "open-matchmaking.direct"
@queue_request "matchmaking.games.search"
require Logger
use AMQP
use Matchmaking.AMQP.Worker.Consumer,
queue: [
name: @queue_request,
routing_key: @queue_request,
durable: true,
passive: true
],
exchange: [
name: @exchange_request,
type: :direct,
durable: true,
passive: true
],
qos: [
prefetch_count: 10
]
# Do something useful with messages
# ...
end
After it I started writing tests for modules, but stuck with issue that happen on setup stage. Running the tests with the same child specification as it used in actual run via mix run or iex -S mix commands, leads to the following error:
1) test Middleware pushes the prepared data about the player to the next stage (MiddlewareWorkerTest)
test/middleware_worker_test.exs:80
** (RuntimeError) failed to start child with the spec %{id: Matchmaking.Middleware.Worker, restart: :transient, start: {
Spotter.Worker, :start_link, [[channel_name: Matchmaking.Middleware.Worker.Channel]]}}.
Reason: an exception was raised:
** (UndefinedFunctionError) function Spotter.Worker.start_link/1 is undefined or private
(spotter) Spotter.Worker.start_link([channel_name: Matchmaking.Middleware.Worker.Channel])
(stdlib) supervisor.erl:379: :supervisor.do_start_child_i/3
(stdlib) supervisor.erl:365: :supervisor.do_start_child/2
(stdlib) supervisor.erl:671: :supervisor.handle_start_child/2
(stdlib) supervisor.erl:420: :supervisor.handle_call/3
(stdlib) gen_server.erl:661: :gen_server.try_handle_call/4
(stdlib) gen_server.erl:690: :gen_server.handle_msg/6
(stdlib) proc_lib.erl:249: :proc_lib.init_p_do_apply/3
stacktrace:
(ex_unit) lib/ex_unit/callbacks.ex:373: ExUnit.Callbacks.start_supervised!/2
test/middleware_worker_test.exs:63: MiddlewareWorkerTest.__ex_unit_setup_0/1
test/middleware_worker_test.exs:1: MiddlewareWorkerTest.__ex_unit__/2
In tests there’s nothing special, just running middleware worker with the same specification as for actual run (sources):
setup_with_mocks([
{
MiddlewareWorker,
[],
[add_user_to_queue: fn(_user_id) -> {:ok, :added} end,
get_player_statistics: fn(_channel_name, _user_id) -> {:ok, @client_data} end]
}
]) do
middleware_worker = start_supervised!(%{
id: Matchmaking.Middleware.Worker,
restart: :transient,
start: {Matchmaking.Middleware.Worker, :start_link, [[channel_name: MiddlewareWorker.Channel]]}
})
{:ok, rabbitmq_client} = start_supervised({AmqpBlockingClient, @rabbitmq_options})
AmqpBlockingClient.configure_channel(rabbitmq_client, @rabbitmq_options)
{:ok, [worker: middleware_worker, client: rabbitmq_client]}
end
Anyone has any ideas why test runner can’t invoke the start_link/1 function, although it truely exists in the module namespace (checked via Matchmaking.Middleware.Worker.module_info call in iex)?
