Start servers for async tests before running tests (#1876)

Close #1874

test/integration_async_helper.rb

@@ -1,14 +1,23 @@
 require File.expand_path('integration_helper', __dir__)
 
 module IntegrationAsyncHelper
+  Server = IntegrationHelper::BaseServer
+
   def it(message, &block)
-    base_port = 5100 + Process.pid % 100
-
-    %w(rainbows puma).each_with_index do |server_name, index|
-      server = IntegrationHelper::BaseServer.new(server_name, base_port + index)
+    Server.all_async.each do |server|
       next unless server.installed?
-
       super("with #{server.name}: #{message}") { server.run_test(self, &block) }
     end
   end
+
+  def self.extend_object(obj)
+    super
+
+    base_port = 5100 + Process.pid % 100
+    servers = %w(rainbows puma)
+
+    servers.each_with_index do |server, index|
+      Server.run(server, base_port+index, async: true)
+    end
+  end
 end

test/integration_helper.rb

@@ -13,12 +13,16 @@ module IntegrationHelper
       @all ||= []
     end
 
+    def self.all_async
+      @all_async ||= []
+    end
+
     def self.each(&block)
       all.each(&block)
     end
 
-    def self.run(server, port)
-      new(server, port).run
+    def self.run(server, port, async: false)
+      new(server, port, async).run
     end
 
     def app_file
@@ -29,9 +33,13 @@ module IntegrationHelper
       "development"
     end
 
-    def initialize(server, port)
+    def initialize(server, port, async)
       @installed, @pipe, @server, @port = nil, nil, server, port
-      Server.all << self
+      if async
+        Server.all_async << self
+      else
+        Server.all << self
+      end
     end
 
     def run
@@ -44,14 +52,7 @@ module IntegrationHelper
 
     def installed?
       return @installed unless @installed.nil?
-      s = case server
-      when 'HTTP'
-        'net/http/server'
-      when 'puma'
-        'puma/rack/handler'
-      else
-        server
-      end
+      s = server == 'HTTP' ? 'net/http/server' : server
       require s
       @installed = true
     rescue LoadError

test/integration_test.rb

@@ -47,7 +47,7 @@ class IntegrationTest < Minitest::Test
     }ix
 
     # because Net HTTP Server logs to $stderr by default
-    assert_match exp, server.log unless server.net_http_server? || server.rainbows?
+    assert_match exp, server.log unless server.net_http_server?
   end
 
   it 'does not generate warnings' do