Improve docs and tests

lib/mint/http.ex

@@ -903,6 +903,9 @@ defmodule Mint.HTTP do
       Contrary to `recv/3`, this function does not return partial responses on errors. Use
       `recv/3` for full control.
 
+  This function only handles responses for the given `request_ref`. Do not use it when making
+  concurrent requests as responses other than for `request_ref` are ignored.
+
   ## Examples
 
       iex> {:ok, conn} = Mint.HTTP.connect(:https, "httpbin.org", 443, mode: :passive)
@@ -922,9 +925,9 @@ defmodule Mint.HTTP do
                headers: [{binary(), binary()}],
                body: binary()
              }
-  def recv_response(conn, ref, timeout)
-      when is_reference(ref) and Util.is_timeout(timeout) do
-    recv_response([], {nil, [], ""}, conn, ref, timeout)
+  def recv_response(conn, request_ref, timeout)
+      when is_reference(request_ref) and Util.is_timeout(timeout) do
+    recv_response([], {nil, [], ""}, conn, request_ref, timeout)
   end
 
   defp recv_response(

test/mint/http1/conn_test.exs

@@ -482,6 +482,32 @@ defmodule Mint.HTTP1Test do
              }
     end
 
+    test "handles trailers", %{port: port, server_ref: server_ref} do
+      assert {:ok, conn} = HTTP1.connect(:http, "localhost", port, mode: :passive)
+      assert_receive {^server_ref, server_socket}
+
+      {:ok, conn, ref} = HTTP1.request(conn, "GET", "/", [], nil)
+
+      :ok = :gen_tcp.send(server_socket, "HTTP/1.1 200 OK\r\n")
+      :ok = :gen_tcp.send(server_socket, "transfer-encoding: chunked\r\n")
+      :ok = :gen_tcp.send(server_socket, "trailer: x-trailer\r\n\r\n")
+      :ok = :gen_tcp.send(server_socket, "5\r\nhello\r\n")
+      :ok = :gen_tcp.send(server_socket, "5\r\nworld\r\n0\r\n")
+      :ok = :gen_tcp.send(server_socket, "x-trailer: foo\r\n\r\n")
+
+      assert {:ok, _conn, response} = Mint.HTTP.recv_response(conn, ref, 100)
+
+      assert response == %{
+               body: "helloworld",
+               headers: [
+                 {"transfer-encoding", "chunked"},
+                 {"trailer", "x-trailer"},
+                 {"x-trailer", "foo"}
+               ],
+               status: 200
+             }
+    end
+
     test "handles errors", %{port: port, server_ref: server_ref} do
       assert {:ok, conn} = HTTP1.connect(:http, "localhost", port, mode: :passive)
       assert_receive {^server_ref, server_socket}

test/mint/http2/conn_test.exs

@@ -2206,6 +2206,55 @@ defmodule Mint.HTTP2Test do
       assert HTTP2.open?(conn)
     end
 
+    test "handles trailers", %{conn: conn} do
+      {conn, ref} = open_request(conn)
+
+      assert_recv_frames [headers(stream_id: stream_id)]
+
+      <<trailer_hbf1::1-bytes, trailer_hbf2::binary>> =
+        server_encode_headers([{"x-trailer", "foo"}])
+
+      data =
+        server_encode_frames([
+          headers(
+            stream_id: stream_id,
+            hbf:
+              server_encode_headers([
+                {":status", "200"},
+                {"content-type", "text/plain"}
+              ]),
+            flags: set_flags(:headers, [:end_headers])
+          ),
+          data(
+            stream_id: stream_id,
+            data: "helloworld",
+            flags: set_flags(:data, [])
+          ),
+          headers(
+            stream_id: stream_id,
+            hbf: trailer_hbf1,
+            flags: set_flags(:headers, [:end_stream])
+          ),
+          continuation(
+            stream_id: stream_id,
+            hbf: trailer_hbf2,
+            flags: set_flags(:continuation, [:end_headers])
+          )
+        ])
+
+      :ok = :ssl.send(server_get_socket(), data)
+
+      assert {:ok, _conn, response} = Mint.HTTP.recv_response(conn, ref, 100)
+
+      assert response == %{
+               body: "helloworld",
+               headers: [{"content-type", "text/plain"}, {"x-trailer", "foo"}],
+               status: 200
+             }
+
+      assert HTTP2.open?(conn)
+    end
+
     test "handles errors", %{conn: conn} do
       {conn, ref} = open_request(conn)
       assert_recv_frames [headers(stream_id: _stream_id)]