feat: return compiler diagnostics from reload

Author: mhanberg

.github/workflows/ci.yaml

@@ -0,0 +1,72 @@
+name: CI
+on:
+  pull_request:
+  push:
+    branches: main
+
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+    name: Test (${{matrix.elixir}}/${{matrix.otp}})
+
+    strategy:
+      fail-fast: false
+      matrix:
+        elixir: [1.17.x, 1.18.x]
+        otp: [26.x, 27.x]
+
+    steps:
+    - uses: actions/checkout@v4
+    - uses: erlef/setup-beam@v1
+      id: install
+      with:
+        otp-version: ${{matrix.otp}}
+        elixir-version: ${{matrix.elixir}}
+    - uses: actions/cache@v4
+      id: cache
+      with:
+        path: |
+          deps
+        key: ${{ runner.os }}-mix-${{steps.install.outputs.otp-version}}-${{steps.install.outputs.elixir-version}}-${{ hashFiles('**/mix.lock') }}
+        restore-keys: |
+          ${{ runner.os }}-mix-${{steps.install.outputs.otp-version}}-${{steps.install.outputs.elixir-version}}-
+
+    - name: Install Dependencies
+      if: steps.cache.outputs.cache-hit != 'true'
+      run: mix deps.get
+
+    - name: Run Tests
+      run: mix test
+
+  formatter:
+    runs-on: ubuntu-latest
+    name: Formatter (${{matrix.elixir}}/${{matrix.otp}})
+
+    strategy:
+      matrix:
+        otp: [27.x]
+        elixir: [1.17.x]
+
+    steps:
+    - uses: actions/checkout@v4
+    - uses: erlef/setup-beam@v1
+      id: install
+      with:
+        otp-version: ${{matrix.otp}}
+        elixir-version: ${{matrix.elixir}}
+    - uses: actions/cache@v4
+      id: cache
+      with:
+        path: |
+          deps
+          _build
+        key: ${{ runner.os }}-mix-${{steps.install.outputs.otp-version}}-${{steps.install.outputs.elixir-version}}-${{ hashFiles('**/mix.lock') }}
+        restore-keys: |
+          ${{ runner.os }}-mix-${{steps.install.outputs.otp-version}}-${{steps.install.outputs.elixir-version}}-
+
+    - name: Install Dependencies
+      if: steps.cache.outputs.cache-hit != 'true'
+      run: mix deps.get
+
+    - name: Run Formatter
+      run: mix format --check-formatted

.gitignore

@@ -24,3 +24,5 @@ web_dev_utils-*.tar
 
 # Temporary files, for example, from tests.
 /tmp/
+
+/test/support/editable.ex

lib/web_dev_utils/code_reloader.ex

@@ -25,12 +25,12 @@ defmodule WebDevUtils.CodeReloader do
     {:ok, :nostate}
   end
 
-  def handle_call(:reload, from, state) do
-    froms = all_waiting([from])
-    mix_compile(Code.ensure_loaded(Mix.Task))
-    Enum.each(froms, &GenServer.reply(&1, :ok))
+  def handle_call(:reload, _from, state) do
+    froms = all_waiting([])
+    result = mix_compile(Code.ensure_loaded(Mix.Task))
+    Enum.each(froms, &GenServer.reply(&1, result))
 
-    {:noreply, state}
+    {:reply, result, state}
   end
 
   defp all_waiting(acc) do
@@ -43,10 +43,11 @@ defmodule WebDevUtils.CodeReloader do
 
   defp mix_compile({:error, _reason}) do
     Logger.error("Could not find Mix")
+    :error
   end
 
   defp mix_compile({:module, Mix.Task}) do
     Mix.Task.reenable("compile.elixir")
-    Mix.Task.run("compile.elixir")
+    Mix.Task.run("compile.elixir", ["--return-errors"])
   end
 end

mix.exs

@@ -10,6 +10,7 @@ defmodule WebDevUtils.MixProject do
         "Library to enable awesome local development for websites and web applications",
       version: "0.2.0",
       elixir: "~> 1.14",
+      elixirc_paths: elixirc_paths(Mix.env()),
       start_permanent: Mix.env() == :prod,
       package: package(),
       deps: deps()
@@ -23,6 +24,10 @@ defmodule WebDevUtils.MixProject do
     ]
   end
 
+  # Specifies which paths to compile per environment.
+  defp elixirc_paths(:test), do: ["lib", "test/support"]
+  defp elixirc_paths(_), do: ["lib"]
+
   # Run "mix help deps" to learn about dependencies.
   defp deps do
     [

test/support/.keep

@@ -0,0 +1,47 @@
+defmodule WebDevUtils.CodeReloaderTest do
+  use ExUnit.Case, async: true
+  import ExUnit.CaptureIO
+
+  alias WebDevUtils.CodeReloader
+
+  setup do
+    on_exit(fn ->
+      File.rm("test/support/editable.ex")
+    end)
+
+    :ok
+  end
+
+  test "noops when nothing has changed" do
+    start_supervised!(CodeReloader)
+
+    assert {_, []} = CodeReloader.reload()
+    assert {:noop, []} == CodeReloader.reload()
+  end
+
+  test "recompiles code" do
+    File.write!("test/support/editable.ex", """
+    defmodule Editable do
+    end
+    """)
+
+    start_supervised!(CodeReloader)
+
+    capture_io(:stderr, fn ->
+      assert {:ok, []} == CodeReloader.reload()
+    end)
+  end
+
+  test "recompiles code and something fails" do
+    File.write!("test/support/editable.ex", """
+    defmodule Editable d
+    end
+    """)
+
+    start_supervised!(CodeReloader)
+
+    capture_io(:stderr, fn ->
+      assert {:error, [%Mix.Task.Compiler.Diagnostic{}]} = CodeReloader.reload()
+    end)
+  end
+end