Fix postgres errors when running tests

test/support/conn_case.ex

@@ -123,7 +123,13 @@ defmodule MvWeb.ConnCase do
   end
 
   setup tags do
-    Mv.DataCase.setup_sandbox(tags)
-    {:ok, conn: Phoenix.ConnTest.build_conn()}
+    pid = Mv.DataCase.setup_sandbox(tags)
+
+    conn = Phoenix.ConnTest.build_conn()
+    # Set metadata for Phoenix.Ecto.SQL.Sandbox plug to allow LiveView processes
+    # to share the test's database connection in async tests
+    conn = Plug.Conn.put_private(conn, :ecto_sandbox, pid)
+
+    {:ok, conn: conn}
   end
 end

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 """