Add live_component handler to the LiveView integration (#50)

* Add LiveView handler for live_component events

This patch adds a new function clause that handles :live_component
events, which is based on the :live_view handle_event implementation,
but doesn't include session data, as that's not present in live
components.

* Detach live_component handlers in LiveViewTest

Because the handlers weren't detached, the test suite started failing
sometimes because events came in twice. By detaching the handlers like
we do for all other events, we only have one set of handlers running in
the test suite.

* Remove extra LiveView clause for live_components

By depending on :appsignal 2.2.16 or above, the event handler can call
set_sample_data with an empty value for metadata without breaking the
call chain, so both function clauses can be merged.

* Add changeset to ecplain live_component handling

"Handle live_component events in LiveView integration"

Co-authored-by: AJ Foster <2789166+aj-foster@users.noreply.github.com>

.changesets/handle-live_component-events-in-liveview-integration.md

@@ -0,0 +1,6 @@
+---
+bump: "patch"
+type: "add"
+---
+
+Handle live_component events in LiveView integration

lib/appsignal_phoenix/live_view.ex

@@ -87,7 +87,7 @@ defmodule Appsignal.Phoenix.LiveView do
   end
 
   def handle_event_start(
-        [:phoenix, :live_view, name, :start],
+        [:phoenix, _type, name, :start],
         %{system_time: system_time},
         metadata,
         _event_name

mix.exs

@@ -54,7 +54,7 @@ defmodule Appsignal.Phoenix.MixProject do
       end
 
     [
-      {:appsignal, ">= 2.2.15 and < 3.0.0"},
+      {:appsignal, ">= 2.2.16 and < 3.0.0"},
       {:appsignal_plug, ">= 2.0.11 and < 3.0.0"},
       {:phoenix, "~> 1.4"},
       {:phoenix_html, "~> 2.11 or ~> 3.0", optional: true},

test/appsignal_phoenix/live_view_test.exs

@@ -236,6 +236,21 @@ defmodule Appsignal.Phoenix.LiveViewTest do
           :telemetry.detach(
             {Appsignal.Phoenix.LiveView, [:phoenix, :live_view, :handle_event, :exception]}
           )
+
+        :ok =
+          :telemetry.detach(
+            {Appsignal.Phoenix.LiveView, [:phoenix, :live_component, :handle_event, :start]}
+          )
+
+        :ok =
+          :telemetry.detach(
+            {Appsignal.Phoenix.LiveView, [:phoenix, :live_component, :handle_event, :stop]}
+          )
+
+        :ok =
+          :telemetry.detach(
+            {Appsignal.Phoenix.LiveView, [:phoenix, :live_component, :handle_event, :exception]}
+          )
       end)
     end
 
@@ -368,6 +383,54 @@ defmodule Appsignal.Phoenix.LiveViewTest do
     end
   end
 
+  describe "handle_event_start/4, with a live_component handle_event event" do
+    setup do
+      event = [:phoenix, :live_component, :handle_event, :start]
+
+      :telemetry.attach(
+        {__MODULE__, event},
+        event,
+        &Appsignal.Phoenix.LiveView.handle_event_start/4,
+        :ok
+      )
+
+      :telemetry.execute(
+        [:phoenix, :live_component, :handle_event, :start],
+        %{monotonic_time: -576_457_566_461_433_920, system_time: 1_653_474_764_790_125_080},
+        %{
+          params: %{foo: "bar"},
+          socket: %Phoenix.LiveView.Socket{view: __MODULE__}
+        }
+      )
+    end
+
+    test "creates a root span with a namespace and a start time" do
+      assert {:ok, [{"live_view", nil, [start_time: 1_653_474_764_790_125_080]}]} =
+               Test.Tracer.get(:create_span)
+    end
+
+    test "sets the span's name" do
+      assert {:ok, [{%Span{}, "Appsignal.Phoenix.LiveViewTest#handle_event"}]} =
+               Test.Span.get(:set_name)
+    end
+
+    test "sets the span's category" do
+      assert {:ok, attributes} = Test.Span.get(:set_attribute)
+
+      assert Enum.any?(attributes, fn {%Span{}, key, data} ->
+               key == "appsignal:category" and data == "handle_event.live_view"
+             end)
+    end
+
+    test "sets the span's params" do
+      assert {:ok, attributes} = Test.Span.get(:set_sample_data)
+
+      assert Enum.any?(attributes, fn {%Span{}, key, data} ->
+               key == "params" and data == %{foo: "bar"}
+             end)
+    end
+  end
+
   describe "handle_event_stop/4" do
     setup do
       event = [:phoenix, :live_view, :mount, :stop]