From cd61f86de8e91f201bbf740c7b4e396c9a1a0202 Mon Sep 17 00:00:00 2001
From: Girish Gopaul <girish@gopaul.me>
Date: Sun, 20 Jul 2025 22:35:34 +0400
Subject: [PATCH] Allow send_resp to be used without a body

This will be useful for sending 204 No Content http status.

Instead of `send_resp(conn, :no_content, "")` we can now do
`send_resp(conn, :no_content)`.
---
 lib/plug/conn.ex             |  4 +++-
 test/plug/conn_test.exs      | 10 ++++++++++
 test/plug/telemetry_test.exs |  8 ++++----
 3 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/lib/plug/conn.ex b/lib/plug/conn.ex
index 141b4c6d..3d39e14e 100644
--- a/lib/plug/conn.ex
+++ b/lib/plug/conn.ex
@@ -590,10 +590,12 @@ defmodule Plug.Conn do
   ## Examples
 
       Plug.Conn.send_resp(conn, 404, "Not found")
+      Plug.Conn.send_resp(conn, 204)
 
   """
+  @spec send_resp(t, status) :: t | no_return
   @spec send_resp(t, status, body) :: t | no_return
-  def send_resp(%Conn{} = conn, status, body) do
+  def send_resp(%Conn{} = conn, status, body \\ "") do
     conn |> resp(status, body) |> send_resp()
   end
 
diff --git a/test/plug/conn_test.exs b/test/plug/conn_test.exs
index c89c1812..a4a0fc2a 100644
--- a/test/plug/conn_test.exs
+++ b/test/plug/conn_test.exs
@@ -282,6 +282,16 @@ defmodule Plug.ConnTest do
     assert get_resp_cookies(conn)["hello"] == %{value: "world"}
   end
 
+  test "send_resp/2 sets the body to empty string" do
+    conn = conn(:get, "/foo")
+    assert conn.state == :unset
+    assert conn.resp_body == nil
+    conn = send_resp(conn, 204)
+    assert conn.status == 204
+    assert conn.resp_body == ""
+    assert conn.state == :sent
+  end
+
   test "send_resp/1 raises if the connection was unset" do
     conn = conn(:get, "/goo")
 
diff --git a/test/plug/telemetry_test.exs b/test/plug/telemetry_test.exs
index 69a514d6..38f9d4e5 100644
--- a/test/plug/telemetry_test.exs
+++ b/test/plug/telemetry_test.exs
@@ -8,9 +8,9 @@ defmodule Plug.TelemetryTest do
     use Plug.Builder
 
     plug Plug.Telemetry, event_prefix: [:pipeline], extra_options: :hello
-    plug :send_resp, 200
+    plug :send_response, 200
 
-    defp send_resp(conn, status) do
+    defp send_response(conn, status) do
       Plug.Conn.send_resp(conn, status, "Response")
     end
   end
@@ -26,13 +26,13 @@ defmodule Plug.TelemetryTest do
 
     plug Plug.Telemetry, event_prefix: [:crashing, :pipeline]
     plug :raise_error
-    plug :send_resp, 200
+    plug :send_response, 200
 
     defp raise_error(_conn, _) do
       raise "Crash!"
     end
 
-    defp send_resp(conn, status) do
+    defp send_response(conn, status) do
       Plug.Conn.send_resp(conn, status, "Response")
     end
   end