Rack::Events on_finish callback is not called in a Rails ActionDispatch::IntegrationTest with a streaming body #2422
Description
With a controller that uses a pattern similar to https://github.com/socketry/falcon-rails-examples/blob/main/app/controllers/sse_controller.rb for SSE:
class SseController < ApplicationController
def index
end
EVENT_STREAM_HEADERS = {
'content-type' => 'text/event-stream',
}
def events
body = proc do |stream|
5.times do
stream.write("data: #{Time.now}\n\n")
sleep 0.05
end
end
self.response = Rack::Response[200, EVENT_STREAM_HEADERS.dup, body]
end
endand a Rack::Events middleware like this:
class RecordEvents
include Rack::Events::Abstract
EVENTS = []
def on_start(request, response)
EVENTS << "on_start"
end
def on_finish(request, response)
EVENTS << "on_finish"
end
endthe following test case
class SseControllerTest < ActionDispatch::IntegrationTest
test "should get index" do
RecordEvents::EVENTS.clear
get sse_index_url
assert_response :success
assert_equal ["on_start", "on_finish"], RecordEvents::EVENTS
end
test "should get events" do
RecordEvents::EVENTS.clear
get sse_events_url
assert_response :success
assert_equal ["on_start", "on_finish"], RecordEvents::EVENTS
end
enddoes not pass:
Failure:
SseControllerTest#test_should_get_events [test/controllers/sse_controller_test.rb:19]:
Expected: ["on_start", "on_finish"]
Actual: ["on_start"]
The "should get index" test works fine, but "should get events" fails to call the on_finish handler.
I have an end-to-end reproduction in this branch: https://github.com/tavianator/falcon-rails-examples/tree/rack-events-sse-test. Just run
$ bundle exec rails test ./test/controllers/sse_controller_test.rb