fix: handle carriage return \r line terminators in SSE (#772)

fix: Handle carriage return \r line terminators in SSE

Author: howleysv

lib/tesla/middleware/sse.ex

@@ -46,7 +46,11 @@ defmodule Tesla.Middleware.SSE do
     |> Stream.chunk_while(
       "",
       fn elem, acc ->
-        {lines, [rest]} = (acc <> elem) |> String.split("\n\n") |> Enum.split(-1)
+        {lines, [rest]} =
+          (acc <> elem)
+          |> String.split(double_linebreak_regex())
+          |> Enum.split(-1)
+
         {:cont, lines, rest}
       end,
       fn
@@ -61,14 +65,16 @@ defmodule Tesla.Middleware.SSE do
 
   defp decode_body(binary, opts) when is_binary(binary) do
     binary
-    |> String.split("\n\n")
+    |> String.split(double_linebreak_regex())
     |> Enum.map(&decode_message/1)
     |> Enum.flat_map(&only(&1, opts[:only]))
   end
 
+  defp double_linebreak_regex(), do: ~r/((\r\n)|((?<!\r)\n)|(\r(?!\n))){2}/
+
   defp decode_message(message) do
     message
-    |> String.split("\n")
+    |> String.split(["\r\n", "\n", "\r"])
     |> Enum.map(&decode_body/1)
     |> Enum.reduce(%{}, fn
       :empty, acc -> acc

test/tesla/middleware/sse_test.exs

@@ -120,5 +120,29 @@ defmodule Tesla.Middleware.SSETest do
 
       assert Enum.to_list(env.body) == [%{data: "data1"}, %{data: "data2"}, %{data: "data3"}]
     end
+
+    test "handle stream data with varying line terminators" do
+      adapter = fn _env ->
+        chunks = [
+          ~s|data: data1\n|,
+          ~s|\ndata: data2\r|,
+          ~s|\r\ndata: data3\r\revent: event4\r|,
+          ~s|\ndata: data4\n\n|
+        ]
+
+        stream = Stream.map(chunks, & &1)
+
+        {:ok, %{@env | body: stream}}
+      end
+
+      assert {:ok, env} = Tesla.Middleware.SSE.call(%Tesla.Env{}, [{:fn, adapter}], [])
+
+      assert Enum.to_list(env.body) == [
+               %{data: "data1"},
+               %{data: "data2"},
+               %{data: "data3"},
+               %{event: "event4", data: "data4"}
+             ]
+    end
   end
 end