🚧✨ Support VANISHED response to #expunge

Both the `QRESYNC` and `UIDONLY` extensions replace `EXPUNGE` responses
with `VANISHED` responses.  This updates the #expunge and #uid_expunge
commands to return VanishedData, rather than a (misleading) empty array.

Author: nevans

lib/net/imap.rb

@@ -1889,18 +1889,39 @@ def unselect
       send_command("UNSELECT")
     end
 
+    # call-seq:
+    #   expunge -> array of message sequence numbers
+    #   expunge -> VanishedData of UIDs
+    #
     # Sends an {EXPUNGE command [IMAP4rev1 §6.4.3]}[https://www.rfc-editor.org/rfc/rfc3501#section-6.4.3]
-    # Sends a EXPUNGE command to permanently remove from the currently
-    # selected mailbox all messages that have the \Deleted flag set.
+    # to permanently remove all messages with the +\Deleted+ flag from the
+    # currently selected mailbox.
     #
     # Related: #uid_expunge
+    #
+    # ==== Capabilities
+    #
+    # When either QRESYNC[https://tools.ietf.org/html/rfc7162] or
+    # UIDONLY[https://tools.ietf.org/html/rfc9586] are enabled, #expunge
+    # returns VanishedData, which contains UIDs---<em>not message sequence
+    # numbers</em>.
+    #
+    # *NOTE:* Any unhandled +VANISHED+ #responses without the +EARLIER+ modifier
+    # will be merged into the VanishedData and deleted from #responses.  This is
+    # consistent with how Net::IMAP handles +EXPUNGE+ responses.  Unhandled
+    # <tt>VANISHED (EARLIER)</tt> responses will _not_ be merged or returned.
+    #
+    # *NOTE:* When no messages are expunged, Net::IMAP currently returns an
+    # empty array, regardless of which extensions have been enabled.  In the
+    # future, an empty VanishedData will be returned instead.
     def expunge
-      synchronize do
-        send_command("EXPUNGE")
-        clear_responses("EXPUNGE")
-      end
+      expunge_internal("EXPUNGE")
     end
 
+    # call-seq:
+    #   uid_expunge -> array of message sequence numbers
+    #   uid_expunge -> VanishedData of UIDs
+    #
     # Sends a {UID EXPUNGE command [RFC4315 §2.1]}[https://www.rfc-editor.org/rfc/rfc4315#section-2.1]
     # {[IMAP4rev2 §6.4.9]}[https://www.rfc-editor.org/rfc/rfc9051#section-6.4.9]
     # to permanently remove all messages that have both the <tt>\\Deleted</tt>
@@ -1924,13 +1945,13 @@ def expunge
     #
     # ==== Capabilities
     #
-    # The server's capabilities must include +UIDPLUS+
+    # The server's capabilities must include either +IMAP4rev2+ or +UIDPLUS+
     # [RFC4315[https://www.rfc-editor.org/rfc/rfc4315.html]].
+    #
+    # Otherwise, #uid_expunge is updated by extensions in the same way as
+    # #expunge.
     def uid_expunge(uid_set)
-      synchronize do
-        send_command("UID EXPUNGE", SequenceSet.new(uid_set))
-        clear_responses("EXPUNGE")
-      end
+      expunge_internal("UID EXPUNGE", SequenceSet.new(uid_set))
     end
 
     # :call-seq:
@@ -3261,6 +3282,21 @@ def enforce_logindisabled?
       end
     end
 
+    def expunge_internal(...)
+      synchronize do
+        send_command(...)
+        vanished_array = extract_responses("VANISHED") { !_1.earlier? }
+        if vanished_array.empty?
+          clear_responses("EXPUNGE")
+        elsif vanished_array.length == 1
+          vanished_array.first
+        else
+          merged_uids = SequenceSet[*vanished_array.map(&:uids)]
+          VanishedData[uids: merged_uids, earlier: false]
+        end
+      end
+    end
+
     RETURN_WHOLE = /\ARETURN\z/i
     RETURN_START = /\ARETURN\b/i
     private_constant :RETURN_WHOLE, :RETURN_START

test/net/imap/test_imap.rb

@@ -1016,7 +1016,7 @@ def test_id
     end
   end
 
-  def test_uidplus_uid_expunge
+  test "#uid_expunge with EXPUNGE responses" do
     with_fake_server(select: "INBOX",
                      extensions: %i[UIDPLUS]) do |server, imap|
       server.on "UID EXPUNGE" do |resp|
@@ -1032,6 +1032,24 @@ def test_uidplus_uid_expunge
     end
   end
 
+  test "#uid_expunge with VANISHED response" do
+    with_fake_server(select: "INBOX",
+                     extensions: %i[UIDPLUS]) do |server, imap|
+      server.on "UID EXPUNGE" do |resp|
+        resp.untagged("VANISHED 1001,1003")
+        resp.done_ok
+      end
+      response = imap.uid_expunge(1000..1003)
+      cmd = server.commands.pop
+      assert_equal ["UID EXPUNGE", "1000:1003"], [cmd.name, cmd.args]
+      assert_equal(
+        Net::IMAP::VanishedData[uids: [1001, 1003], earlier: false],
+        response
+      )
+      assert_equal([], imap.clear_responses("VANISHED"))
+    end
+  end
+
   def test_uidplus_appenduid
     with_fake_server(select: "INBOX",
                      extensions: %i[UIDPLUS]) do |server, imap|
@@ -1168,6 +1186,65 @@ def test_enable
     end
   end
 
+  test "#expunge with EXPUNGE responses" do
+    with_fake_server(select: "INBOX") do |server, imap|
+      server.on "EXPUNGE" do |resp|
+        resp.untagged("1 EXPUNGE")
+        resp.untagged("1 EXPUNGE")
+        resp.untagged("99 EXPUNGE")
+        resp.done_ok
+      end
+      response = imap.expunge
+      cmd = server.commands.pop
+      assert_equal ["EXPUNGE", nil], [cmd.name, cmd.args]
+      assert_equal [1, 1, 99], response
+      assert_equal [], imap.clear_responses("EXPUNGED")
+    end
+  end
+
+  test "#expunge with a VANISHED response" do
+    with_fake_server(select: "INBOX") do |server, imap|
+      server.on "EXPUNGE" do |resp|
+        resp.untagged("VANISHED 15:456")
+        resp.done_ok
+      end
+      response = imap.expunge
+      cmd = server.commands.pop
+      assert_equal ["EXPUNGE", nil], [cmd.name, cmd.args]
+      assert_equal(
+        Net::IMAP::VanishedData[uids: [15..456], earlier: false],
+        response
+      )
+      assert_equal([], imap.clear_responses("VANISHED"))
+    end
+  end
+
+  test "#expunge with multiple VANISHED responses" do
+    with_fake_server(select: "INBOX") do |server, imap|
+      server.unsolicited("VANISHED 86")
+      server.on "EXPUNGE" do |resp|
+        resp.untagged("VANISHED (EARLIER) 1:5,99,123")
+        resp.untagged("VANISHED 15,456")
+        resp.untagged("VANISHED (EARLIER) 987,1001")
+        resp.done_ok
+      end
+      response = imap.expunge
+      cmd = server.commands.pop
+      assert_equal ["EXPUNGE", nil], [cmd.name, cmd.args]
+      assert_equal(
+        Net::IMAP::VanishedData[uids: [15, 86, 456], earlier: false],
+        response
+      )
+      assert_equal(
+        [
+          Net::IMAP::VanishedData[uids: [1..5, 99, 123], earlier: true],
+          Net::IMAP::VanishedData[uids: [987, 1001],     earlier: true],
+        ],
+        imap.clear_responses("VANISHED")
+      )
+    end
+  end
+
   def test_close
     with_fake_server(select: "inbox") do |server, imap|
       resp = imap.close