Enable concurrent Wallaby tests

config/test.exs

@@ -6,6 +6,8 @@ config :chess, ChessWeb.Endpoint,
   http: [port: 4001],
   server: true
 
+config :chess, :sql_sandbox, true
+
 # Print only warnings and errors during test
 config :logger, level: :warn
 

lib/chess_web/endpoint.ex

@@ -1,6 +1,10 @@
 defmodule ChessWeb.Endpoint do
   use Phoenix.Endpoint, otp_app: :chess
 
+  if Application.get_env(:chess, :sql_sandbox) do
+    plug Phoenix.Ecto.SQL.Sandbox
+  end
+
   socket "/socket", ChessWeb.UserSocket
 
   # Serve at "/" the static files from "priv/static" directory.