✨ Add response_handlers kwarg to Net::IMAP.new (backport #419 to 0.4)

lib/net/imap.rb

@@ -233,8 +233,9 @@ module Net
   # Use paginated or limited versions of commands whenever possible.
   #
   # Use #add_response_handler to handle responses after each one is received.
-  # Use #extract_responses, #clear_responses, or #responses (with a block) to
-  # prune responses.
+  # Use the +response_handlers+ argument to ::new to assign response handlers
+  # before the receiver thread is started.  Use #extract_responses,
+  # #clear_responses, or #responses (with a block) to prune responses.
   #
   # == Errors
   #
@@ -881,6 +882,12 @@ def idle_response_timeout;  config.idle_response_timeout   end
     #
     #   See DeprecatedClientOptions.new for deprecated SSL arguments.
     #
+    # [response_handlers]
+    #   A list of response handlers to be added before the receiver thread is
+    #   started.  This ensures every server response is handled, including the
+    #   #greeting.  Note that the greeting is handled in the current thread, but
+    #   all other responses are handled in the receiver thread.
+    #
     # [config]
     #   A Net::IMAP::Config object to use as the basis for #config.  By default,
     #   the global Net::IMAP.config is used.
@@ -952,7 +959,7 @@ def idle_response_timeout;  config.idle_response_timeout   end
     # [Net::IMAP::ByeResponseError]
     #   Connected to the host successfully, but it immediately said goodbye.
     #
-    def initialize(host, port: nil, ssl:  nil,
+    def initialize(host, port: nil, ssl: nil, response_handlers: nil,
                    config: Config.global, **config_options)
       super()
       # Config options
@@ -975,6 +982,7 @@ def initialize(host, port: nil, ssl:  nil,
       @receiver_thread = nil
       @receiver_thread_exception = nil
       @receiver_thread_terminating = false
+      response_handlers&.each do add_response_handler(_1) end
 
       # Client Protocol Sender (including state for currently running commands)
       @tag_prefix = "RUBY"
@@ -2756,6 +2764,10 @@ def response_handlers
     #     end
     #   }
     #
+    # Response handlers can also be added when the client is created before the
+    # receiver thread is started, by the +response_handlers+ argument to ::new.
+    # This ensures every server response is handled, including the #greeting.
+    #
     # Related: #remove_response_handler, #response_handlers
     def add_response_handler(handler = nil, &block)
       raise ArgumentError, "two Procs are passed" if handler && block
@@ -2782,6 +2794,7 @@ def remove_response_handler(handler)
     def start_imap_connection
       @greeting        = get_server_greeting
       @capabilities    = capabilities_from_resp_code @greeting
+      @response_handlers.each do |handler| handler.call(@greeting) end
       @receiver_thread = start_receiver_thread
     rescue Exception
       @sock.close

test/net/imap/test_imap_response_handlers.rb

@@ -0,0 +1,92 @@
+# frozen_string_literal: true
+
+require "net/imap"
+require "test/unit"
+require_relative "fake_server"
+
+class IMAPResponseHandlersTest < Test::Unit::TestCase
+  include Net::IMAP::FakeServer::TestHelper
+
+  def setup
+    Net::IMAP.config.reset
+    @do_not_reverse_lookup = Socket.do_not_reverse_lookup
+    Socket.do_not_reverse_lookup = true
+    @threads = []
+  end
+
+  def teardown
+    if !@threads.empty?
+      assert_join_threads(@threads)
+    end
+  ensure
+    Socket.do_not_reverse_lookup = @do_not_reverse_lookup
+  end
+
+  test "#add_response_handlers" do
+    responses = []
+    with_fake_server do |server, imap|
+      server.on("NOOP") do |resp|
+        3.times do resp.untagged("#{_1 + 1} EXPUNGE") end
+        resp.done_ok
+      end
+
+      assert_equal 0, imap.response_handlers.length
+      imap.add_response_handler do responses << [:block, _1] end
+      assert_equal 1, imap.response_handlers.length
+      imap.add_response_handler(->{ responses << [:proc, _1] })
+      assert_equal 2, imap.response_handlers.length
+
+      imap.noop
+      responses = responses[0, 6].map {|which, resp|
+        [which, resp.class, resp.name, resp.data]
+      }
+      assert_equal [
+        [:block, Net::IMAP::UntaggedResponse, "EXPUNGE", 1],
+        [:proc,  Net::IMAP::UntaggedResponse, "EXPUNGE", 1],
+        [:block, Net::IMAP::UntaggedResponse, "EXPUNGE", 2],
+        [:proc,  Net::IMAP::UntaggedResponse, "EXPUNGE", 2],
+        [:block, Net::IMAP::UntaggedResponse, "EXPUNGE", 3],
+        [:proc,  Net::IMAP::UntaggedResponse, "EXPUNGE", 3],
+      ], responses
+    end
+  end
+
+  test "::new with response_handlers kwarg" do
+    greeting = nil
+    expunges = []
+    alerts   = []
+    untagged = 0
+    handler0 = ->{ greeting ||= _1 }
+    handler1 = ->(r) { alerts   << r.data.text if r.data.code.name == "ALERT" rescue nil }
+    handler2 = ->(r) { expunges << r.data if r.name == "EXPUNGE" }
+    handler3 = ->(r) { untagged += 1 if r.is_a?(Net::IMAP::UntaggedResponse) }
+    response_handlers = [handler0, handler1, handler2, handler3]
+
+    run_fake_server_in_thread do |server|
+      port = server.port
+      imap = Net::IMAP.new("localhost", port: port,
+                           response_handlers: response_handlers)
+      assert_equal response_handlers, imap.response_handlers
+      refute_same  response_handlers, imap.response_handlers
+
+      # handler0 recieved the greeting and handler3 counted it
+      assert_equal imap.greeting, greeting
+      assert_equal 1, untagged
+
+      server.on("NOOP") do |resp|
+        resp.untagged "1 EXPUNGE"
+        resp.untagged "1 EXPUNGE"
+        resp.untagged "OK [ALERT] The first alert."
+        resp.done_ok  "[ALERT] Did you see the alert?"
+      end
+
+      imap.noop
+      assert_equal 4, untagged
+      assert_equal [1, 1], expunges # from handler2
+      assert_equal ["The first alert.", "Did you see the alert?"], alerts
+    ensure
+      imap&.logout! unless imap&.disconnected?
+    end
+  end
+
+end