quality: Add some test cases for openflow messages

lib/openflow/features/reply.ex

@@ -11,11 +11,38 @@ defmodule Openflow.Features.Reply do
 
   alias __MODULE__
 
+  @type t :: %Reply{
+          version: 4,
+          xid: 0..0xFFFFFFFF,
+          datapath_id: String.t() | nil,
+          n_buffers: 0..0xFFFFFFFF,
+          n_tables: 0..0xFF,
+          aux_id: 0..0xFF,
+          capabilities: [
+            :flow_stats
+            | :table_stats
+            | :port_stats
+            | :group_stats
+            | :ip_reasm
+            | :queue_stats
+            | :arp_match_ip
+            | :port_blocked
+          ]
+        }
+
+  @spec ofp_type :: 6
   def ofp_type, do: 6
 
-  def read(
-        <<datapath_id::64-bits, n_buf::32, n_tab::8, aux_id::8, _pad::16, caps_int::32, _rsv::32>>
-      ) do
+  @spec read(<<_::192>>) :: t()
+  def read(<<
+        datapath_id::64-bits,
+        n_buf::32,
+        n_tab::8,
+        aux_id::8,
+        _pad::16,
+        caps_int::32,
+        _rsv::32
+      >>) do
     dpid = Openflow.Utils.to_hex_string(datapath_id)
     flags = Openflow.Enums.int_to_flags(caps_int, :switch_capabilities)
 
@@ -28,6 +55,7 @@ defmodule Openflow.Features.Reply do
     }
   end
 
+  @spec to_binary(t()) :: <<_::192>>
   def to_binary(%Reply{
         datapath_id: datapath_id,
         n_buffers: n_buf,