Merge pull request #304 from BinaryNoggin/check-for-input-callback

Warns missing `handle_input/3` on `request_input/2`

Author: crertel

lib/scenic/scene.ex

@@ -722,7 +722,10 @@ defmodule Scenic.Scene do
   def request_input(scene, input_class)
   def request_input(scene, input) when is_atom(input), do: request_input(scene, [input])
 
-  def request_input(%Scene{viewport: vp, pid: pid}, inputs) when is_list(inputs) do
+  def request_input(%Scene{viewport: vp, pid: pid, module: module}, inputs) when is_list(inputs) do
+    unless Kernel.function_exported?(module, :handle_input, 3) do
+      Logger.warn("Requesting input for #{inspect inputs} - #{module}.handle_input/3 not implemented")
+    end
     ViewPort.Input.request(vp, inputs, pid: pid)
   end
 

test/scenic/scene_test.exs

@@ -13,6 +13,8 @@ defmodule Scenic.SceneTest do
   alias Scenic.Script
   import Scenic.Components
 
+  import ExUnit.CaptureLog
+
   @root_id ViewPort.root_id()
 
   # import IEx
@@ -68,6 +70,23 @@ defmodule Scenic.SceneTest do
       scene = assign(scene, pid: pid)
       {:ok, scene}
     end
+
+    @impl Scenic.Scene
+    def handle_input(input, id, %{assigns: %{pid: pid}} = scene) do
+      send(pid, {:input_test, input, id})
+      {:noreply, scene}
+    end
+  end
+
+  defmodule TestSceneNoInputHandler do
+    use Scenic.Scene
+
+    @impl Scenic.Scene
+    def init(scene, pid, _opts) do
+      Process.send(pid, {:up, scene}, [])
+      scene = assign(scene, pid: pid)
+      {:ok, scene}
+    end
   end
 
   @codepoint {:codepoint, {"k", []}}
@@ -402,6 +421,20 @@ defmodule Scenic.SceneTest do
            ~> {:ok, sorted_list([:cursor_pos, :cursor_button, :codepoint])}
   end
 
+  test "request_input warns when handle_input is not implements" do
+    Scenic.Test.ViewPort.start({TestSceneNoInputHandler, self()})
+
+    scene =
+      receive do
+        {:up, scene} -> scene
+      end
+
+    assert capture_log(fn ->
+      Scenic.Scene.request_input(scene, [:key])
+    end)
+    =~ "handle_input/3 not implemented"
+  end
+
   test "unrequest_input works", %{scene: scene} do
     Scenic.Scene.request_input(scene, :cursor_button)
 

test/scenic/view_port/input_test.exs

@@ -27,6 +27,10 @@ defmodule Scenic.ViewPort.InputTest do
     # def handle_input( input, %{assigns: %{pid: pid}} = scene ) do
     #   Process.send( pid, {:test_input, input}, [] )
     # end
+
+    def handle_input(_, _, scene) do
+      {:noreply, scene}
+    end
   end
 
   setup do