Update docs & test

Author: wojtekmach

lib/mint/http.ex

@@ -900,6 +900,11 @@ defmodule Mint.HTTP do
       Contrary to `recv/3`, this function does not return partial responses on errors. Use
       `recv/3` for full control.
 
+  > #### Error {: .error}
+  >
+  > This function can only be used for one-off requests. If there is another concurrent request,
+  > started by `request/5`, it will crash.
+
   ## Options
 
     * `:timeout` - the maximum amount of time in milliseconds waiting to receive the response.
@@ -979,8 +984,9 @@ defmodule Mint.HTTP do
   end
 
   # Ignore entries from other requests.
-  defp recv_response([_entry | rest], acc, conn, ref, timeout) do
-    recv_response(rest, acc, conn, ref, timeout)
+  defp recv_response([entry | _rest], _acc, _conn, _ref, _timeout) when is_tuple(entry) do
+    ref = elem(entry, 1)
+    raise "received unexpected response from request #{inspect(ref)}"
   end
 
   defp recv_response([], acc, conn, ref, timeout) do

test/mint/http1/conn_test.exs

@@ -528,6 +528,28 @@ defmodule Mint.HTTP1Test do
 
       refute HTTP1.open?(conn)
     end
+
+    test "raises on multiple requests " do
+      {:ok, port, server_ref} =
+        TestServer.start(fn %{socket: socket} ->
+          :ok = :gen_tcp.send(socket, "HTTP/1.1 200 OK\r\n")
+          :ok = :gen_tcp.send(socket, "content-type: text/plain\r\n")
+          :ok = :gen_tcp.send(socket, "content-length: 10\r\n\r\n")
+          :ok = :gen_tcp.send(socket, "hello")
+          :ok = :gen_tcp.send(socket, "world")
+        end)
+
+      assert {:ok, conn} = HTTP1.connect(:http, "localhost", port, mode: :passive)
+      assert_receive {^server_ref, _server_socket}
+
+      {:ok, conn, ref} = Mint.HTTP.request(conn, "GET", "/", [], nil)
+
+      assert_raise RuntimeError,
+                   "received unexpected response from request #{inspect(ref)}",
+                   fn ->
+                     Mint.HTTP.request_and_response(conn, "GET", "/", [], nil)
+                   end
+    end
   end
 
   test "changing the connection mode with set_mode/2",

test/support/mint/http1/test_server.ex

@@ -1,17 +1,17 @@
 defmodule Mint.HTTP1.TestServer do
-  def start do
+  def start(fun \\ nil) do
     {:ok, listen_socket} = :gen_tcp.listen(0, mode: :binary, packet: :raw)
     server_ref = make_ref()
     parent = self()
 
-    spawn_link(fn -> loop(listen_socket, parent, server_ref) end)
+    spawn_link(fn -> loop(listen_socket, parent, server_ref, fun) end)
 
     with {:ok, port} <- :inet.port(listen_socket) do
       {:ok, port, server_ref}
     end
   end
 
-  defp loop(listen_socket, parent, server_ref) do
+  defp loop(listen_socket, parent, server_ref, fun) do
     case :gen_tcp.accept(listen_socket) do
       {:ok, socket} ->
         send(parent, {server_ref, socket})
@@ -22,7 +22,11 @@ defmodule Mint.HTTP1.TestServer do
           {:error, :einval} -> :ok
         end
 
-        loop(listen_socket, parent, server_ref)
+        if fun do
+          fun.(%{socket: socket, parent: parent})
+        end
+
+        loop(listen_socket, parent, server_ref, fun)
 
       {:error, :closed} ->
         :ok