Task: Add tests for TraceService and CallbackTracingServer (#290)

* Add ModuleDiscoveryService.all_modules test

* wip

* Add tests for TraceService

* Refactor

* Add tests for CallbackTracingServer

* Change receive/send to sleep/exit

* Ignore LiveDebuggerDev in test coverage

* Add tracing mechanism tests

* Remove duplicate test

* Update TraceService test

* Update CallbackTracingServer tests

* Change test to async

* Refactor

* Add verify_on_exit

Author: hhubert6

mix.exs

@@ -16,7 +16,10 @@ defmodule LiveDebugger.MixProject do
       name: "LiveDebugger",
       source_url: "https://github.com/software-mansion/live-debugger",
       description: "Tool for debugging LiveView applications",
-      docs: docs()
+      docs: docs(),
+      test_coverage: [
+        ignore_modules: [~r/^LiveDebuggerDev\./, DevWeb]
+      ]
     ]
   end
 

test/gen_servers/callback_tracing_server_test.exs

@@ -0,0 +1,195 @@
+defmodule LiveDebugger.GenServers.CallbackTracingServerTest do
+  @moduledoc false
+  use ExUnit.Case, async: true
+
+  import Mox
+
+  alias LiveDebugger.Structs.Trace
+  alias LiveDebugger.GenServers.CallbackTracingServer
+  alias LiveDebugger.Utils.PubSub, as: PubSubUtils
+  alias LiveDebugger.MockModuleService
+  alias LiveDebugger.MockDbg
+  alias LiveDebugger.MockEtsTableServer
+  alias LiveDebugger.MockPubSubUtils
+  alias LiveDebugger.MockProcessService
+
+  @modules [
+    CoolApp.LiveViews.UserDashboard,
+    CoolApp.Service.UserService,
+    CoolApp.LiveComponent.UserElement
+  ]
+
+  setup :verify_on_exit!
+
+  test "init/1" do
+    assert {:ok, %{}} = CallbackTracingServer.init([])
+    assert_receive :setup_tracing
+  end
+
+  test "handle_call/3" do
+    assert {:reply, :ok, %{}} == CallbackTracingServer.handle_call(:ping, self(), %{})
+  end
+
+  test "proper tracing setup" do
+    MockModuleService
+    |> expect(:all, fn ->
+      Enum.map(@modules, fn module -> {to_charlist(module), ~c"", false} end)
+    end)
+    |> expect(:loaded?, 6, fn _module -> true end)
+    |> expect(:behaviours, 6, fn module -> get_behaviours(module) end)
+
+    MockDbg
+    |> expect(:tracer, fn :process, {_handler, 0} -> :ok end)
+    |> expect(:p, fn :all, :c -> :ok end)
+
+    get_live_view_callbacks(CoolApp.LiveViews.UserDashboard)
+    |> Enum.each(&expect(MockDbg, :tp, fn &1, [] -> :ok end))
+
+    get_live_component_callbacks(CoolApp.LiveComponent.UserElement)
+    |> Enum.each(&expect(MockDbg, :tp, fn &1, [] -> :ok end))
+
+    MockDbg
+    |> expect(:tp, fn {Phoenix.LiveView.Diff, :delete_component, 2}, [] -> :ok end)
+
+    assert {:noreply, %{}} = CallbackTracingServer.handle_info(:setup_tracing, %{})
+  end
+
+  describe "tracing mechanism" do
+    setup do
+      parent = self()
+
+      MockModuleService
+      |> expect(:all, fn -> [] end)
+
+      MockDbg
+      |> expect(:p, fn :all, :c -> :ok end)
+      |> expect(:tp, fn {Phoenix.LiveView.Diff, :delete_component, 2}, [] -> :ok end)
+      |> expect(:tracer, fn :process, {handle_trace, 0} -> send(parent, handle_trace) end)
+
+      :ok
+    end
+
+    test "handle delete component trace" do
+      parent = self()
+      transport_pid = :c.pid(0, 0, 1)
+      pid = :c.pid(0, 0, 2)
+      cid = 3
+      socket_id = "phx-GDrDzLLr4USWzwBC"
+      module = Phoenix.LiveView.Diff
+      function = :delete_component
+      args = [cid, %{}]
+
+      expected_topic =
+        PubSubUtils.component_deleted_topic(%{socket_id: socket_id, transport_pid: transport_pid})
+
+      MockProcessService
+      |> expect(:state, fn ^pid ->
+        {:ok, LiveDebugger.Fakes.state(transport_pid: transport_pid, socket_id: socket_id)}
+      end)
+
+      MockPubSubUtils
+      |> expect(:broadcast, fn ^expected_topic, {:new_trace, trace} ->
+        send(parent, {:trace, trace})
+      end)
+
+      assert {:noreply, %{}} = CallbackTracingServer.handle_info(:setup_tracing, %{})
+
+      assert_receive handle_trace
+      assert 0 == handle_trace.({:trace, pid, :call, {module, function, args}}, 0)
+      assert_receive {:trace, trace}
+
+      assert %Trace{
+               id: 0,
+               module: ^module,
+               function: ^function,
+               arity: 2,
+               args: ^args,
+               socket_id: ^socket_id,
+               transport_pid: ^transport_pid,
+               pid: ^pid,
+               cid: %Phoenix.LiveComponent.CID{cid: ^cid}
+             } = trace
+    end
+
+    test "handle standard live view trace" do
+      transport_pid = :c.pid(0, 0, 1)
+      pid = :c.pid(0, 0, 2)
+      socket_id = "phx-GDrDzLLr4USWzwBC"
+      module = CoolApp.LiveViews.UserDashboard
+      function = :handle_info
+
+      args = [
+        :msg,
+        %{transport_pid: transport_pid, socket: %Phoenix.LiveView.Socket{id: socket_id}}
+      ]
+
+      table = :ets.new(:test_table, [:ordered_set, :public])
+
+      expected_tsnf_topic = PubSubUtils.tsnf_topic(socket_id, transport_pid, pid, function)
+      expected_ts_f_topic = PubSubUtils.ts_f_topic(socket_id, transport_pid, function)
+
+      MockEtsTableServer
+      |> expect(:table!, fn ^pid -> table end)
+
+      MockPubSubUtils
+      |> expect(:broadcast, fn ^expected_tsnf_topic, {:new_trace, _trace} -> :ok end)
+      |> expect(:broadcast, fn ^expected_ts_f_topic, {:new_trace, _trace} -> :ok end)
+
+      assert {:noreply, %{}} = CallbackTracingServer.handle_info(:setup_tracing, %{})
+      assert_receive handle_trace
+      assert -1 == handle_trace.({:trace, pid, :call, {module, function, args}}, 0)
+      assert [{0, trace}] = :ets.tab2list(table)
+
+      assert %Trace{
+               id: 0,
+               module: ^module,
+               function: ^function,
+               arity: 2,
+               args: ^args,
+               socket_id: ^socket_id,
+               transport_pid: ^transport_pid,
+               pid: ^pid,
+               cid: nil
+             } = trace
+    end
+
+    test "handle unexpected trace" do
+      assert {:noreply, %{}} = CallbackTracingServer.handle_info(:setup_tracing, %{})
+      assert_receive handle_trace
+      assert 0 == handle_trace.({:_, :c.pid(0, 0, 1), :_, {SomeModule, :some_func, []}}, 0)
+    end
+  end
+
+  defp get_behaviours(module) do
+    case module do
+      CoolApp.LiveViews.UserDashboard -> [Phoenix.LiveView]
+      CoolApp.Service.UserService -> []
+      CoolApp.LiveComponent.UserElement -> [Phoenix.LiveComponent]
+    end
+  end
+
+  defp get_live_view_callbacks(module) do
+    [
+      {module, :mount, 3},
+      {module, :handle_params, 3},
+      {module, :handle_info, 2},
+      {module, :handle_call, 3},
+      {module, :handle_cast, 2},
+      {module, :terminate, 2},
+      {module, :render, 1},
+      {module, :handle_event, 3},
+      {module, :handle_async, 3}
+    ]
+  end
+
+  defp get_live_component_callbacks(module) do
+    [
+      {module, :mount, 1},
+      {module, :update, 2},
+      {module, :update_many, 1},
+      {module, :render, 1},
+      {module, :handle_event, 3},
+      {module, :handle_async, 3}
+    ]
+  end
+end

test/gen_servers/ets_table_server_test.exs

@@ -2,9 +2,13 @@ defmodule LiveDebugger.GenServers.EtsTableServerTest do
   @moduledoc false
   use ExUnit.Case, async: true
 
+  import Mox
+
   alias LiveDebugger.Utils.PubSub, as: PubSubUtils
   alias LiveDebugger.GenServers.EtsTableServer
 
+  setup :verify_on_exit!
+
   test "start_link/1" do
     assert {:ok, _pid} = EtsTableServer.start_link()
     GenServer.stop(EtsTableServer)
@@ -19,7 +23,7 @@ defmodule LiveDebugger.GenServers.EtsTableServerTest do
       pid = :c.pid(0, 0, 1)
 
       LiveDebugger.MockEtsTableServer
-      |> Mox.expect(:table!, fn ^pid -> :some_ref end)
+      |> expect(:table!, fn ^pid -> :some_ref end)
 
       assert :some_ref = EtsTableServer.table!(pid)
     end
@@ -28,7 +32,7 @@ defmodule LiveDebugger.GenServers.EtsTableServerTest do
       pid = :c.pid(0, 0, 1)
 
       LiveDebugger.MockEtsTableServer
-      |> Mox.expect(:delete_table!, fn ^pid -> :ok end)
+      |> expect(:delete_table!, fn ^pid -> :ok end)
 
       assert :ok = EtsTableServer.delete_table!(pid)
     end
@@ -47,7 +51,7 @@ defmodule LiveDebugger.GenServers.EtsTableServerTest do
       topic = PubSubUtils.process_status_topic(pid)
 
       LiveDebugger.MockPubSubUtils
-      |> Mox.expect(:broadcast, fn ^topic, {:process_status, :dead} -> :ok end)
+      |> expect(:broadcast, fn ^topic, {:process_status, :dead} -> :ok end)
 
       assert {:noreply, new_table_refs} =
                EtsTableServer.handle_info({:DOWN, :_, :process, pid, :_}, table_refs)