Correct error message and add concurrency detection spec.

Author: dblock

CHANGELOG.md

@@ -1,7 +1,8 @@
 ### 0.16.1 (Next)
 
-* Your contribution here.
 * [#359](https://github.com/slack-ruby/slack-ruby-client/pull/359): Handle non-JSON 500 errors - [@agrobbin](https://github.com/agrobbin).
+* [#360](https://github.com/slack-ruby/slack-ruby-client/pull/360): Remove faye-websocket from the concurrency detection error message - [@dblock](https://github.com/dblock).
+* Your contribution here.
 
 ### 0.16.0 (2021/01/24)
 

lib/slack/real_time/config.rb

@@ -38,19 +38,9 @@ def concurrency
       private
 
       def detect_concurrency
-        %i[Async].each do |concurrency|
-          begin
-            return Slack::RealTime::Concurrency.const_get(concurrency)
-          rescue LoadError, NameError
-            false # could not be loaded, missing dependencies
-          end
-        end
-
-        raise(
-          NoConcurrencyError,
-          'Missing concurrency. Add async-websocket or faye-websocket ' \
-          'to your Gemfile.'
-        )
+        Slack::RealTime::Concurrency.const_get(:Async)
+      rescue LoadError, NameError
+        raise NoConcurrencyError, 'Missing concurrency. Add async-websocket to your Gemfile.'
       end
     end
 

lib/slack/web/api/slack-api-ref

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+require 'spec_helper'
+
+RSpec.describe 'with CONCURRENCY', skip: ( # rubocop:disable RSpec/DescribeClass
+  (!ENV['CONCURRENCY']) && 'missing CONCURRENCY'
+) do
+  it 'detects concurrency' do
+    expect(Slack::RealTime::Config.concurrency).to eq Slack::RealTime::Concurrency::Async
+  end
+end

spec/slack/real_time/concurrency/with_concurrency_spec.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+require 'spec_helper'
+
+RSpec.describe 'without CONCURRENCY', skip: ( # rubocop:disable RSpec/DescribeClass
+  (ENV['CONCURRENCY']) && 'CONCURRENCY is set'
+) do
+  it 'raises NoConcurrencyError' do
+    expect { Slack::RealTime::Config.concurrency }.to raise_error Slack::RealTime::Config::NoConcurrencyError
+  end
+end

spec/slack/real_time/concurrency/without_concurrency_spec.rb

@@ -3,7 +3,7 @@
 
 #
 # to re-record a rtm_connect fixture run with
-# SLACK_API_TOKEN=... CONCURRENCY=faye-websocket rspec spec/slack/real_time/rtm_connect_spec.rb
+# SLACK_API_TOKEN=... CONCURRENCY=async-websocket rspec spec/slack/real_time/rtm_connect_spec.rb
 # edit rtm_connect.yml and remove the token, fix wss:// path (run specs, fix failures)
 #
 

spec/slack/real_time/rtm_connect_spec.rb

@@ -3,7 +3,7 @@
 
 #
 # to re-record a rtm_start fixture run with
-# SLACK_API_TOKEN=... CONCURRENCY=faye-websocket rspec spec/slack/real_time/rtm_start_spec.rb
+# SLACK_API_TOKEN=... CONCURRENCY=async-websocket rspec spec/slack/real_time/rtm_start_spec.rb
 # edit rtm_start.yml and remove the token, fix wss:// path (run specs, fix failures)
 #