Fix postgres errors when running tests

test/support/data_case.ex

@@ -34,10 +34,12 @@ defmodule Mv.DataCase do
 
   @doc """
   Sets up the sandbox based on the test tags.
+  Returns the owner pid for use with Phoenix.Ecto.SQL.Sandbox.
   """
   def setup_sandbox(tags) do
     pid = Ecto.Adapters.SQL.Sandbox.start_owner!(Mv.Repo, shared: not tags[:async])
     on_exit(fn -> Ecto.Adapters.SQL.Sandbox.stop_owner(pid) end)
+    pid
   end
 
   @doc """