Use the default organization as default for new notebooks (#2183)

lib/livebook/session.ex

@@ -891,7 +891,11 @@ defmodule Livebook.Session do
   """
   @spec default_notebook() :: Notebook.t()
   def default_notebook() do
-    %{Notebook.new() | sections: [%{Section.new() | cells: [Cell.new(:code)]}]}
+    %{
+      Notebook.new()
+      | sections: [%{Section.new() | cells: [Cell.new(:code)]}],
+        hub_id: Livebook.Hubs.get_default_hub().id
+    }
   end
 
   defp schedule_autosave(state) do

test/livebook/session_test.exs

@@ -1906,6 +1906,40 @@ defmodule Livebook.SessionTest do
     assert_receive {:operation, {:add_cell_evaluation_output, _, ^cell_id, ^expected_output}}
   end
 
+  defmodule Global do
+    use ExUnit.Case, async: false
+
+    describe "default hub for new notebooks" do
+      test "use the default hub as default for new notebooks" do
+        hub = Livebook.Factory.insert_hub(:team)
+        Livebook.Hubs.set_default_hub(hub.id)
+        notebook = Livebook.Session.default_notebook()
+
+        assert notebook.hub_id == hub.id
+        Livebook.Hubs.delete_hub(hub.id)
+      end
+
+      test "fallback to personal-hub when there's no default" do
+        hub = Livebook.Factory.insert_hub(:team)
+        Livebook.Hubs.unset_default_hub(hub.id)
+        notebook = Livebook.Session.default_notebook()
+
+        assert notebook.hub_id == "personal-hub"
+        Livebook.Hubs.delete_hub(hub.id)
+      end
+
+      test "fallback to personal-hub when the default doesn't exist" do
+        hub = Livebook.Factory.insert_hub(:team)
+        Livebook.Hubs.set_default_hub(hub.id)
+        Livebook.Hubs.delete_hub(hub.id)
+        notebook = Livebook.Session.default_notebook()
+
+        refute Livebook.Hubs.hub_exists?(hub.id)
+        assert notebook.hub_id == "personal-hub"
+      end
+    end
+  end
+
   defp start_session(opts \\ []) do
     opts = Keyword.merge([id: Utils.random_id()], opts)
     pid = start_supervised!({Session, opts}, id: opts[:id])

test/livebook_teams/web/hub/edit_live_test.exs

@@ -7,7 +7,7 @@ defmodule LivebookWeb.Integration.Hub.EditLiveTest do
   alias Livebook.Hubs
 
   setup %{user: user, node: node} do
-    Livebook.Hubs.subscribe([:crud, :connection, :secrets, :default])
+    Livebook.Hubs.subscribe([:crud, :connection, :secrets])
     hub = create_team_hub(user, node)
     id = hub.id