Channel response timeout

[dustinfarris]

Summary

The assert_reply channel test macro times out on the first test that invokes Absinthe.run and returns a result.

Details

This PR contains models for Chat.Message and Chat.User, a new schema field message, and a "graphql" channel that takes a standard GraphQL query, runs it through Absinthe, and returns the result.

There is a test that verifies that this works. The test creates a Message, sends a message query to the graphql channel, and listens for a reply using the assert_reply macro. assert_reply, by default, times out after 100ms.

There are actually two tests that are nearly identical. The only difference is the test on line 44 uses assert_reply's default timeout. The test on line 28 increases the timeout to 300ms.

I am using Elixir 1.4.0 and Erlang 19.2

To reproduce

Clone this repo:

git clone [email protected]:dustinfarris/phoenix_chat_example
cd phoenix_chat_example && git checkout channel-timeout
mix do deps.get, compile

Run the default timeout test:

mix test test/message_query_test.exs:44

The test fails:

  1) test message query (Chat.MessageQueryTest)
     test/message_query_test.exs:44
     No message matching %Phoenix.Socket.Reply{ref: ^ref, status: :ok, payload: %{data: %{"message" => %{"body" => "Test message", "author" => %{"name" => "Dustin Farris"}}}}} after 100ms.
     The following variables were pinned:
       ref = #Reference<0.0.2.17387>
     The process mailbox is empty.
     stacktrace:
       test/message_query_test.exs:50: (test)

That "The process mailbox is empty." line is a result of the assertion timing out before a message was received.

Now, run the test where the timeout is increased to 300ms

mix test test/message_query_test.exs:28

The test passes:

.

Finished in 0.2 seconds

Now—and this is interesting—run both tests:

mix test test/message_query_test.exs

Both tests pass:

..

Finished in 0.2 seconds

---

I have observed that only the first test that runs will fail with this timeout error, if it is left at the default 100ms. From that point on everything passes.

[josevalim]

Related to phoenixframework/phoenix#2023.

If Absinthe is doing some lazy compilation, that would be it. Otherwise it may be code loading.