diff --git a/lib/livebook/session.ex b/lib/livebook/session.ex
index 22baff901..6b34f4aaa 100644
--- a/lib/livebook/session.ex
+++ b/lib/livebook/session.ex
@@ -158,6 +158,24 @@ defmodule Livebook.Session do
     GenServer.call(pid, :get_notebook, @timeout)
   end
 
+  @doc """
+  Subscribes to update in sessions list.
+
+  ## Messages
+
+    * `:session_closed`
+    * `{:session_updated, session}`
+    * `{:hydrate_bin_entries, entries}`
+    * `{:operation, operation}`
+    * `{:error, error}`
+    * `{:info, info}`
+
+  """
+  @spec subscribe(id()) :: :ok | {:error, term()}
+  def subscribe(session_id) do
+    Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session_id}")
+  end
+
   @doc """
   Computes the file name for download.
 
@@ -1205,7 +1223,7 @@ defmodule Livebook.Session do
 
   defp after_operation(state, prev_state, {:client_join, _client_pid, user}) do
     unless Map.has_key?(prev_state.data.users_map, user.id) do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "users:#{user.id}")
+      Livebook.Users.subscribe(user.id)
     end
 
     state
@@ -1215,7 +1233,7 @@ defmodule Livebook.Session do
     user_id = prev_state.data.clients_map[client_pid]
 
     unless Map.has_key?(state.data.users_map, user_id) do
-      Phoenix.PubSub.unsubscribe(Livebook.PubSub, "users:#{user_id}")
+      Livebook.Users.unsubscribe(user_id)
     end
 
     state
diff --git a/lib/livebook/sessions.ex b/lib/livebook/sessions.ex
index 52d5b38b9..d71353085 100644
--- a/lib/livebook/sessions.ex
+++ b/lib/livebook/sessions.ex
@@ -14,8 +14,6 @@ defmodule Livebook.Sessions do
   Spawns a new `Session` process with the given options.
 
   Makes the session globally visible within the session tracker.
-
-  `{:session_created, session}` gets broadcasted under the "tracker_sessions" topic.
   """
   @spec create_session(keyword()) :: {:ok, Session.t()} | {:error, any()}
   def create_session(opts \\ []) do
@@ -73,11 +71,24 @@ defmodule Livebook.Sessions do
 
   @doc """
   Updates the given session info across the cluster.
-
-  `{:session_updated, session}` gets broadcasted under the "tracker_sessions" topic.
   """
   @spec update_session(Session.t()) :: :ok | {:error, any()}
   def update_session(session) do
     Livebook.Tracker.update_session(session)
   end
+
+  @doc """
+  Subscribes to update in sessions list.
+
+  ## Messages
+
+    * `{:session_created, session}`
+    * `{:session_updated, session}`
+    * `{:session_closed, session}`
+
+  """
+  @spec subscribe() :: :ok | {:error, term()}
+  def subscribe() do
+    Phoenix.PubSub.subscribe(Livebook.PubSub, "tracker_sessions")
+  end
 end
diff --git a/lib/livebook/system_resources.ex b/lib/livebook/system_resources.ex
index 65a4950de..c54480840 100644
--- a/lib/livebook/system_resources.ex
+++ b/lib/livebook/system_resources.ex
@@ -16,6 +16,19 @@ defmodule Livebook.SystemResources do
     :ets.lookup_element(@name, :memory, 2)
   end
 
+  @doc """
+  Subscribes to resource usage updates.
+
+  ## Messages
+
+    * `{:memory_update, memory}`
+
+  """
+  @spec subscribe() :: :ok | {:error, term()}
+  def subscribe() do
+    Phoenix.PubSub.subscribe(Livebook.PubSub, "system_resources")
+  end
+
   @doc """
   Updates the resources kept by this process.
   """
diff --git a/lib/livebook/users.ex b/lib/livebook/users.ex
index c7abc3cc2..604f3e6d2 100644
--- a/lib/livebook/users.ex
+++ b/lib/livebook/users.ex
@@ -17,4 +17,25 @@ defmodule Livebook.Users do
   defp broadcast_user_message(user_id, message) do
     Phoenix.PubSub.broadcast(Livebook.PubSub, "users:#{user_id}", message)
   end
+
+  @doc """
+  Subscribes to updates in user information.
+
+  ## Messages
+
+    * `{:user_change, user}`
+
+  """
+  @spec subscribe(User.id()) :: :ok | {:error, term()}
+  def subscribe(user_id) do
+    Phoenix.PubSub.subscribe(Livebook.PubSub, "users:#{user_id}")
+  end
+
+  @doc """
+  Unsubscribes from `subscribe/1`.
+  """
+  @spec unsubscribe(User.id()) :: :ok
+  def unsubscribe(user_id) do
+    Phoenix.PubSub.unsubscribe(Livebook.PubSub, "users:#{user_id}")
+  end
 end
diff --git a/lib/livebook_web/live/home_live.ex b/lib/livebook_web/live/home_live.ex
index 57ef6f5e1..3d7c41f46 100644
--- a/lib/livebook_web/live/home_live.ex
+++ b/lib/livebook_web/live/home_live.ex
@@ -10,8 +10,8 @@ defmodule LivebookWeb.HomeLive do
   @impl true
   def mount(params, _session, socket) do
     if connected?(socket) do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "tracker_sessions")
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "system_resources")
+      Livebook.Sessions.subscribe()
+      Livebook.SystemResources.subscribe()
     end
 
     sessions = Sessions.list_sessions()
diff --git a/lib/livebook_web/live/hooks/user_hook.ex b/lib/livebook_web/live/hooks/user_hook.ex
index dec7b815e..797333ed3 100644
--- a/lib/livebook_web/live/hooks/user_hook.ex
+++ b/lib/livebook_web/live/hooks/user_hook.ex
@@ -5,7 +5,7 @@ defmodule LivebookWeb.UserHook do
 
   def on_mount(:default, _params, %{"current_user_id" => current_user_id} = session, socket) do
     if connected?(socket) do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "users:#{current_user_id}")
+      Livebook.Users.subscribe(current_user_id)
     end
 
     socket =
diff --git a/lib/livebook_web/live/session_live.ex b/lib/livebook_web/live/session_live.ex
index c0b391952..c00c72c44 100644
--- a/lib/livebook_web/live/session_live.ex
+++ b/lib/livebook_web/live/session_live.ex
@@ -19,7 +19,7 @@ defmodule LivebookWeb.SessionLive do
         data =
           if connected?(socket) do
             data = Session.register_client(session_pid, self(), socket.assigns.current_user)
-            Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session_id}")
+            Session.subscribe(session_id)
 
             data
           else
diff --git a/lib/livebook_web/live/session_live/attached_live.ex b/lib/livebook_web/live/session_live/attached_live.ex
index e008fe66c..489657807 100644
--- a/lib/livebook_web/live/session_live/attached_live.ex
+++ b/lib/livebook_web/live/session_live/attached_live.ex
@@ -10,7 +10,7 @@ defmodule LivebookWeb.SessionLive.AttachedLive do
     end
 
     if connected?(socket) do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
     end
 
     {:ok,
diff --git a/lib/livebook_web/live/session_live/elixir_standalone_live.ex b/lib/livebook_web/live/session_live/elixir_standalone_live.ex
index 0f0e2dc6e..201aeaa82 100644
--- a/lib/livebook_web/live/session_live/elixir_standalone_live.ex
+++ b/lib/livebook_web/live/session_live/elixir_standalone_live.ex
@@ -10,7 +10,7 @@ defmodule LivebookWeb.SessionLive.ElixirStandaloneLive do
     end
 
     if connected?(socket) do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
     end
 
     {:ok, assign(socket, session: session, current_runtime: current_runtime, error_message: nil)}
diff --git a/lib/livebook_web/live/session_live/embedded_live.ex b/lib/livebook_web/live/session_live/embedded_live.ex
index 75fbbcebd..5476e2252 100644
--- a/lib/livebook_web/live/session_live/embedded_live.ex
+++ b/lib/livebook_web/live/session_live/embedded_live.ex
@@ -10,7 +10,7 @@ defmodule LivebookWeb.SessionLive.EmbeddedLive do
     end
 
     if connected?(socket) do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
     end
 
     {:ok, assign(socket, session: session, current_runtime: current_runtime)}
diff --git a/lib/livebook_web/live/session_live/mix_standalone_live.ex b/lib/livebook_web/live/session_live/mix_standalone_live.ex
index f326901a3..99fa2f39f 100644
--- a/lib/livebook_web/live/session_live/mix_standalone_live.ex
+++ b/lib/livebook_web/live/session_live/mix_standalone_live.ex
@@ -12,7 +12,7 @@ defmodule LivebookWeb.SessionLive.MixStandaloneLive do
     end
 
     if connected?(socket) do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
     end
 
     {:ok,
diff --git a/test/livebook/session_test.exs b/test/livebook/session_test.exs
index 036c67f7a..bf3aa9818 100644
--- a/test/livebook/session_test.exs
+++ b/test/livebook/session_test.exs
@@ -41,7 +41,7 @@ defmodule Livebook.SessionTest do
 
   describe "set_notebook_attributes/2" do
     test "sends an attributes update to subscribers", %{session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       pid = self()
 
       attrs = %{set_notebook_attributes: true}
@@ -52,7 +52,7 @@ defmodule Livebook.SessionTest do
 
   describe "insert_section/2" do
     test "sends an insert opreation to subscribers", %{session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       pid = self()
 
       Session.insert_section(session.pid, 0)
@@ -62,7 +62,7 @@ defmodule Livebook.SessionTest do
 
   describe "insert_cell/4" do
     test "sends an insert opreation to subscribers", %{session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       pid = self()
 
       Session.insert_section(session.pid, 0)
@@ -75,7 +75,7 @@ defmodule Livebook.SessionTest do
 
   describe "delete_section/3" do
     test "sends a delete opreation to subscribers", %{session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       pid = self()
 
       {section_id, _cell_id} = insert_section_and_cell(session.pid)
@@ -87,7 +87,7 @@ defmodule Livebook.SessionTest do
 
   describe "delete_cell/2" do
     test "sends a delete opreation to subscribers", %{session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       pid = self()
 
       {_section_id, cell_id} = insert_section_and_cell(session.pid)
@@ -99,7 +99,7 @@ defmodule Livebook.SessionTest do
 
   describe "restore_cell/2" do
     test "sends a restore opreation to subscribers", %{session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       pid = self()
 
       {_section_id, cell_id} = insert_section_and_cell(session.pid)
@@ -118,7 +118,7 @@ defmodule Livebook.SessionTest do
 
       session = start_session(notebook: notebook)
 
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       pid = self()
 
       Session.convert_smart_cell(session.pid, smart_cell.id)
@@ -140,7 +140,7 @@ defmodule Livebook.SessionTest do
       runtime = connected_noop_runtime()
       Session.set_runtime(session.pid, runtime)
 
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
 
       Session.add_dependencies(session.pid, [{:kino, "~> 0.5.0"}])
 
@@ -171,7 +171,7 @@ defmodule Livebook.SessionTest do
       runtime = connected_noop_runtime()
       Session.set_runtime(session.pid, runtime)
 
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
 
       Session.add_dependencies(session.pid, [{:kino, "~> 0.5.0"}])
 
@@ -182,7 +182,7 @@ defmodule Livebook.SessionTest do
   describe "queue_cell_evaluation/2" do
     test "triggers evaluation and sends update operation once it finishes",
          %{session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       pid = self()
 
       {_section_id, cell_id} = insert_section_and_cell(session.pid)
@@ -199,7 +199,7 @@ defmodule Livebook.SessionTest do
 
   describe "cancel_cell_evaluation/2" do
     test "sends a cancel evaluation operation to subscribers", %{session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       pid = self()
 
       {_section_id, cell_id} = insert_section_and_cell(session.pid)
@@ -213,7 +213,7 @@ defmodule Livebook.SessionTest do
 
   describe "set_notebook_name/2" do
     test "sends a notebook name update operation to subscribers", %{session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       pid = self()
 
       Session.set_notebook_name(session.pid, "Cat's guide to life")
@@ -223,7 +223,7 @@ defmodule Livebook.SessionTest do
 
   describe "set_section_name/3" do
     test "sends a section name update operation to subscribers", %{session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       pid = self()
 
       {section_id, _cell_id} = insert_section_and_cell(session.pid)
@@ -235,7 +235,7 @@ defmodule Livebook.SessionTest do
 
   describe "apply_cell_delta/4" do
     test "sends a cell delta operation to subscribers", %{session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       pid = self()
 
       {_section_id, cell_id} = insert_section_and_cell(session.pid)
@@ -252,7 +252,7 @@ defmodule Livebook.SessionTest do
 
   describe "report_cell_revision/3" do
     test "sends a revision report operation to subscribers", %{session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       pid = self()
 
       {_section_id, cell_id} = insert_section_and_cell(session.pid)
@@ -265,7 +265,7 @@ defmodule Livebook.SessionTest do
 
   describe "set_cell_attributes/3" do
     test "sends an attributes update operation to subscribers", %{session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       pid = self()
 
       {_section_id, cell_id} = insert_section_and_cell(session.pid)
@@ -278,7 +278,7 @@ defmodule Livebook.SessionTest do
 
   describe "connect_runtime/2" do
     test "sends a runtime update operation to subscribers", %{session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       pid = self()
 
       runtime = connected_noop_runtime()
@@ -290,7 +290,7 @@ defmodule Livebook.SessionTest do
 
   describe "disconnect_runtime/1" do
     test "sends a runtime update operation to subscribers", %{session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       pid = self()
 
       runtime = connected_noop_runtime()
@@ -310,7 +310,7 @@ defmodule Livebook.SessionTest do
     @tag :tmp_dir
     test "sends a file update operation to subscribers",
          %{session: session, tmp_dir: tmp_dir} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       pid = self()
 
       tmp_dir = FileSystem.File.local(tmp_dir <> "/")
@@ -327,7 +327,7 @@ defmodule Livebook.SessionTest do
       file = FileSystem.File.resolve(tmp_dir, "notebook.livemd")
       start_session(file: file)
 
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
 
       Session.set_file(session.pid, file)
 
@@ -389,7 +389,7 @@ defmodule Livebook.SessionTest do
       # Perform a change, so the notebook is dirty
       Session.set_notebook_name(session.pid, "My notebook")
 
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
 
       assert {:ok, false} = FileSystem.File.exists?(file)
 
@@ -407,7 +407,7 @@ defmodule Livebook.SessionTest do
       # Perform a change, so the notebook is dirty
       Session.set_notebook_name(session.pid, "My notebook")
 
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
 
       assert {:ok, false} = FileSystem.File.exists?(file)
 
@@ -428,7 +428,7 @@ defmodule Livebook.SessionTest do
       # Perform a change, so the notebook is dirty
       Session.set_notebook_name(session.pid, "My notebook")
 
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
 
       assert {:ok, false} = FileSystem.File.exists?(file)
 
@@ -502,7 +502,7 @@ defmodule Livebook.SessionTest do
   test "starts a standalone runtime upon first evaluation if there was none set explicitly" do
     session = start_session()
 
-    Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+    Session.subscribe(session.id)
 
     {_section_id, cell_id} = insert_section_and_cell(session.pid)
 
@@ -517,7 +517,7 @@ defmodule Livebook.SessionTest do
     session = start_session()
     {:ok, runtime} = Runtime.ElixirStandalone.new() |> Runtime.connect()
 
-    Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+    Session.subscribe(session.id)
 
     # Wait for the runtime to be set
     Session.set_runtime(session.pid, runtime)
@@ -535,7 +535,7 @@ defmodule Livebook.SessionTest do
     user = Livebook.Users.User.new()
     Session.register_client(session.pid, self(), user)
 
-    Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+    Session.subscribe(session.id)
 
     updated_user = %{user | name: "Jake Peralta"}
     Livebook.Users.broadcast_change(updated_user)
@@ -581,7 +581,7 @@ defmodule Livebook.SessionTest do
 
       cell_id = code_cell.id
 
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       Session.queue_cell_evaluation(session.pid, cell_id)
 
       assert_receive {:operation,
@@ -605,7 +605,7 @@ defmodule Livebook.SessionTest do
 
       cell_id = code_cell.id
 
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       Session.queue_cell_evaluation(session.pid, cell_id)
 
       assert_receive {:operation,
@@ -630,7 +630,7 @@ defmodule Livebook.SessionTest do
         {:runtime_smart_cell_definitions, [%{kind: "text", name: "Text", requirement: nil}]}
       )
 
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
 
       send(
         session.pid,
@@ -770,7 +770,7 @@ defmodule Livebook.SessionTest do
 
     notebook_glob = Path.join(tmp_dir, "**/*.livemd")
 
-    Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+    Session.subscribe(session.id)
 
     Session.save(session.pid)
     assert_receive {:operation, {:mark_as_not_dirty, _}}
diff --git a/test/livebook/sessions_test.exs b/test/livebook/sessions_test.exs
index ac8777f84..66f48b941 100644
--- a/test/livebook/sessions_test.exs
+++ b/test/livebook/sessions_test.exs
@@ -10,7 +10,7 @@ defmodule Livebook.SessionsTest do
     end
 
     test "broadcasts a message to subscribers" do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "tracker_sessions")
+      Sessions.subscribe()
       {:ok, %{id: id}} = Sessions.create_session()
       assert_receive {:session_created, %{id: ^id}}
     end
@@ -38,7 +38,7 @@ defmodule Livebook.SessionsTest do
   describe "update_session/1" do
     test "broadcasts a message to subscribers" do
       {:ok, %{id: id} = session} = Sessions.create_session()
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "tracker_sessions")
+      Sessions.subscribe()
       updated_session = %{session | notebook_name: "New name"}
       Livebook.Sessions.update_session(updated_session)
       assert_receive {:session_updated, %{id: ^id, notebook_name: "New name"}}
diff --git a/test/livebook/users_test.exs b/test/livebook/users_test.exs
index 92807472f..5300dd2a3 100644
--- a/test/livebook/users_test.exs
+++ b/test/livebook/users_test.exs
@@ -7,7 +7,7 @@ defmodule Livebook.UsersTest do
   describe "broadcast_change/1" do
     test "notifies subscribers of user change" do
       user = User.new()
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "users:#{user.id}")
+      Users.subscribe(user.id)
 
       Users.broadcast_change(user)
 
diff --git a/test/livebook_web/live/home_live_test.exs b/test/livebook_web/live/home_live_test.exs
index 666c00c85..5ce53d0bf 100644
--- a/test/livebook_web/live/home_live_test.exs
+++ b/test/livebook_web/live/home_live_test.exs
@@ -129,7 +129,7 @@ defmodule LivebookWeb.HomeLiveTest do
     end
 
     test "updates UI whenever a session is added or deleted", %{conn: conn} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "tracker_sessions")
+      Sessions.subscribe()
 
       {:ok, view, _} = live(conn, "/")
 
diff --git a/test/livebook_web/live/session_live_test.exs b/test/livebook_web/live/session_live_test.exs
index 5b5aba628..39f260eb0 100644
--- a/test/livebook_web/live/session_live_test.exs
+++ b/test/livebook_web/live/session_live_test.exs
@@ -114,7 +114,7 @@ defmodule LivebookWeb.SessionLiveTest do
     end
 
     test "queueing cell evaluation", %{conn: conn, session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       evaluate_setup(session.pid)
 
       section_id = insert_section(session.pid)
@@ -131,7 +131,7 @@ defmodule LivebookWeb.SessionLiveTest do
     end
 
     test "reevaluting the setup cell", %{conn: conn, session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       evaluate_setup(session.pid)
 
       {:ok, view, _} = live(conn, "/sessions/#{session.id}")
@@ -238,7 +238,7 @@ defmodule LivebookWeb.SessionLiveTest do
         destination: test
       }
 
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
 
       insert_cell_with_output(session.pid, section_id, {:input, input})
 
@@ -267,7 +267,7 @@ defmodule LivebookWeb.SessionLiveTest do
         destination: test
       }
 
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
 
       insert_cell_with_output(session.pid, section_id, {:input, input})
 
@@ -305,7 +305,7 @@ defmodule LivebookWeb.SessionLiveTest do
         reset_on_submit: []
       }
 
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
 
       insert_cell_with_output(session.pid, section_id, {:control, form_control})
 
@@ -330,7 +330,7 @@ defmodule LivebookWeb.SessionLiveTest do
 
   describe "outputs" do
     test "stdout output update", %{conn: conn, session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       evaluate_setup(session.pid)
 
       section_id = insert_section(session.pid)
@@ -351,7 +351,7 @@ defmodule LivebookWeb.SessionLiveTest do
     end
 
     test "frame output update", %{conn: conn, session: session} do
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
       evaluate_setup(session.pid)
 
       section_id = insert_section(session.pid)
@@ -414,7 +414,7 @@ defmodule LivebookWeb.SessionLiveTest do
          %{conn: conn, session: session} do
       {:ok, view, _} = live(conn, "/sessions/#{session.id}/settings/runtime")
 
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
 
       view
       |> element("button", "Elixir standalone")
@@ -599,7 +599,7 @@ defmodule LivebookWeb.SessionLiveTest do
          %{conn: conn, session: session} do
       {:ok, view, _} = live(conn, "/sessions/#{session.id}")
 
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
 
       user1 = create_user_with_name("Jake Peralta")
 
@@ -635,7 +635,7 @@ defmodule LivebookWeb.SessionLiveTest do
 
       {:ok, view, _} = live(conn, "/sessions/#{session.id}")
 
-      Phoenix.PubSub.subscribe(Livebook.PubSub, "sessions:#{session.id}")
+      Session.subscribe(session.id)
 
       assert render(view) =~ "Jake Peralta"