Fix double incrementing of the packet number

lib/tds/messages.ex

@@ -601,7 +601,7 @@ defmodule Tds.Messages do
   end
 
   def encode_packets(type, data, id) do
-    header = encode_header(type, data, id: id + 1, status: 1)
+    header = encode_header(type, data, id: id, status: 1)
     [header <> data]
   end
 

test/messages_test.exs

@@ -0,0 +1,113 @@
+defmodule MessagesTest do
+  use ExUnit.Case, async: true
+
+  describe "encode_packets" do
+    test "data length < 4088 is encoded into one packet" do
+      assert [<<
+               # type
+               0x10,
+               # status
+               0x1,
+               # length
+               0x0,
+               0x9,
+               # channel
+               0x0,
+               0x0,
+               # packet number
+               0x1,
+               # window
+               0x0,
+               # data
+               0xFF
+             >>] == Tds.Messages.encode_packets(0x10, <<0xFF>>)
+    end
+
+    test "data length == 4087 is encoded into one packet" do
+      data = :binary.copy(<<0xFF>>, 4087)
+      assert [<<
+               # type
+               0x10,
+               # status
+               0x1,
+               # length
+               0x0F,
+               0xFF,
+               # channel
+               0x0,
+               0x0,
+               # packet number
+               0x1,
+               # window
+               0x0,
+               data::binary
+              >>] == Tds.Messages.encode_packets(0x10, data)
+    end
+
+    test "data length == 4088 is encoded into one packet" do
+      data = :binary.copy(<<0xFF>>, 4088)
+      assert [[<<
+               # type
+               0x10,
+               # status
+               0x1,
+               # length
+               0x10,
+               0x00,
+               # channel
+               0x0,
+               0x0,
+               # packet number
+               0x1,
+               # window
+               0x0
+              >>, <<
+               # data
+               data::binary
+             >>]] == Tds.Messages.encode_packets(0x10, data)
+    end
+
+    test "data length == 4089 is encoded into two packets " do
+      part1 = :binary.copy(<<0xFF>>, 4088)
+      part2 = :binary.copy(<<0xFF>>, 1)
+      data = part1 <> part2
+      assert [[<<
+               # type
+               0x10,
+               # status
+               0x0,
+               # length
+               0x10,
+               0x00,
+               # channel
+               0x0,
+               0x0,
+               # packet number
+               0x1,
+               # window
+               0x0 >>,
+              <<
+               # data
+               part1::binary
+             >>],
+               <<
+               # type
+               0x10,
+               # status
+               0x1,
+               # length
+               0x0,
+               0x9,
+               # channel
+               0x0,
+               0x0,
+               # packet number
+               0x2,
+               # window
+               0x0,
+               # data
+               0xFF
+             >>] == Tds.Messages.encode_packets(0x10, data)
+    end
+  end
+end