Charts disabled plug testing

lib/trento_web/plugs/charts_disabled_plug.ex

@@ -19,7 +19,7 @@ defmodule TrentoWeb.Plugs.ChartsDisabledPlug do
   @spec call(Plug.Conn.t(), any) :: Plug.Conn.t()
   def call(conn, _) do
     conn
-    |> put_status(501)
+    |> put_resp_content_type("application/json")
     |> resp(
       501,
       Jason.encode!(

test/trento_web/plugs/charts_disabled_plug_test.exs

@@ -0,0 +1,22 @@
+defmodule TrentoWeb.Plugs.ChartsDisabledPlugTest do
+  use TrentoWeb.ConnCase, async: true
+  use Plug.Test
+
+  alias TrentoWeb.Plugs.ChartsDisabledPlug
+
+  test "should return 501 when called" do
+    conn = conn(:get, "/foo")
+
+    conn = ChartsDisabledPlug.call(conn, [])
+
+    assert %{
+             "errors" => [
+               %{
+                 "detail" =>
+                   "Charts endpoints are disabled, check the documentation for further details",
+                 "title" => "Not implemented"
+               }
+             ]
+           } = json_response(conn, 501)
+  end
+end