✅ Move various IMAP client tests to their own files

test/lib/helper.rb

@@ -45,6 +45,21 @@ def teardown
     end
   end
 
+  module SimpleTCPServerHelper
+    private
+
+    def start_server
+      th = Thread.new do
+        yield
+      end
+      @threads << th
+      sleep 0.001 until th.stop?
+    end
+
+    def create_tcp_server = TCPServer.new(server_addr, 0)
+    def server_addr       = Addrinfo.tcp("localhost", 0).ip_address
+  end
+
   def wait_for_response_count(imap, type:, count:,
                               timeout: 0.5, interval: 0.001)
     deadline = Time.now + timeout

test/net/imap/test_command_data.rb

@@ -3,6 +3,8 @@
 require "net/imap"
 require "test/unit"
 
+# For integration testing of sending of command arguments (over a real socket),
+# see test_imap_sending_command_data.rb.
 class CommandDataTest < Net::IMAP::TestCase
   DataFormatError = Net::IMAP::DataFormatError