Implement LIST OVERVIEW.FMT

lib/nntp/tiny/session.py

@@ -375,9 +375,28 @@ class Session():
 
         return self.end()
 
+    OVERVIEW_FMT_HEADERS = [
+        'Subject',
+        'From',
+        'Date',
+        'Message-ID',
+        'References',
+        'Bytes',
+        'Lines',
+    ]
+
+    def _cmd_list_overview_fmt(self):
+        self.respond(ResponseCode.NNTP_INFORMATION_FOLLOWS, "Order of fields in overview database")
+
+        for header in self.OVERVIEW_FMT_HEADERS:
+            self.print("%s:" % (header,))
+
+        return self.end()
+
     LIST_SUBCOMMANDS = {
-        'NEWSGROUPS': _cmd_list_newsgroups,
-        'ACTIVE':     _cmd_list_active,
+        'NEWSGROUPS':   _cmd_list_newsgroups,
+        'ACTIVE':       _cmd_list_active,
+        'OVERVIEW.FMT': _cmd_list_overview_fmt,
     }
 
     def _cmd_list(self, *args):