imap NOTIFY: Flush any pending notifications on NOOP

This is mainly to allow testing NOTIFY easily with imaptest scripts.
This is cheap anyway, because mailbox_list_notify_flush() doesn't do any
syscalls when there's no work.

src/imap/cmd-noop.c

@@ -1,9 +1,15 @@
 /* Copyright (c) 2002-2017 Dovecot authors, see the included COPYING file */
 
 #include "imap-common.h"
+#include "imap-notify.h"
 #include "imap-commands.h"
 
 bool cmd_noop(struct client_command_context *cmd)
 {
+	if (cmd->client->notify_ctx != NULL) {
+		/* flush any delayed notifications now. this is mainly useful
+		   for testing. */
+		imap_notify_flush(cmd->client->notify_ctx);
+	}
 	return cmd_sync(cmd, 0, IMAP_SYNC_FLAG_SAFE, "OK NOOP completed.");
 }

src/imap/imap-notify.c

@@ -522,3 +522,13 @@ void imap_notify_deinit(struct imap_notify_context **_ctx)
 		imap_fetch_free(&ctx->fetch_ctx);
 	pool_unref(&ctx->pool);
 }
+
+void imap_notify_flush(struct imap_notify_context *ctx)
+{
+	struct imap_notify_namespace *notify_ns;
+
+	array_foreach_modifiable(&ctx->namespaces, notify_ns) {
+		if (notify_ns->notify != NULL)
+			mailbox_list_notify_flush(notify_ns->notify);
+	}
+}

src/imap/imap-notify.h

@@ -69,4 +69,6 @@ void imap_client_notify_command_freed(struct client *client);
 int imap_notify_begin(struct imap_notify_context *ctx);
 void imap_notify_deinit(struct imap_notify_context **ctx);
 
+void imap_notify_flush(struct imap_notify_context *ctx);
+
 #endif