feat: implement multi-tier test architecture with runtime detection

- Add comprehensive runtime detection in test_helper.exs
  - Detect Bun and Deno availability
  - Automatically exclude runtime-dependent tests when runtimes missing
  - Conditionally start ReactServer only when runtime available

- Tag all test files by category
  - @moduletag :unit - Pure Elixir tests (cache, config, telemetry)
  - @moduletag :integration - Full integration tests with runtimes
  - @moduletag :requires_runtime - Tests needing Bun or Deno

- Fix template test assertion
  - Update Deno template test to expect versioned import (react-dom@18)

- Update GitHub Actions test workflow
  - Add Bun setup via oven-sh/setup-bun@v1
  - Add Deno setup via denoland/setup-deno@v1
  - Install inotify-tools for file watching support

Test organization:
- Unit tests run without runtime dependencies (fast feedback)
- Integration tests validate real runtime behavior (comprehensive)
- Easy local dev: 'mix test --only unit' or 'mix test --exclude integration'

Resolves test failures in CI by allowing tests to run without runtimes

Author: GSMLG-BOT

.github/workflows/test.yml

@@ -20,6 +20,19 @@ jobs:
           elixir-version: '1.18'
           otp-version: '28'
 
+      - name: Setup Bun
+        uses: oven-sh/setup-bun@v1
+        with:
+          bun-version: latest
+
+      - name: Setup Deno
+        uses: denoland/setup-deno@v1
+        with:
+          deno-version: v1.x
+
+      - name: Install system dependencies
+        run: sudo apt-get update && sudo apt-get install -y inotify-tools
+
       - name: Cache dependencies
         uses: actions/cache@v4
         with:

test/phoenix/mix/build/deno_integration_test.exs

@@ -1,6 +1,8 @@
 defmodule Mix.Tasks.Phx.React.Deno.BundleIntegrationTest do
   use ExUnit.Case, async: false
 
+  @moduletag :integration
+
   alias Mix.Tasks.Phx.React.Deno.Bundle
 
   describe "bundle integration tests" do

test/phoenix/mix/build/deno_test.exs

@@ -1,6 +1,8 @@
 defmodule Mix.Tasks.Phx.React.Deno.BundleTest do
   use ExUnit.Case, async: false
 
+  @moduletag :unit
+
   alias Mix.Tasks.Phx.React.Deno.Bundle
 
   describe "run/1" do

test/phoenix/mix/build/server_deno_template_test.exs

@@ -1,6 +1,8 @@
 defmodule Mix.Tasks.Phx.React.Deno.ServerTemplateTest do
   use ExUnit.Case, async: true
 
+  @moduletag :unit
+
   describe "server_deno.js.eex template" do
     test "template compiles correctly with sample files" do
       files = [
@@ -37,7 +39,7 @@ defmodule Mix.Tasks.Phx.React.Deno.ServerTemplateTest do
 
       assert String.contains?(
                result,
-               "import { renderToReadableStream, renderToString, renderToStaticMarkup } from \"npm:react-dom/server\""
+               "import { renderToReadableStream, renderToString, renderToStaticMarkup } from \"npm:react-dom@18/server\""
              )
 
       # Check that environment variables are used

test/phoenix/react_server/cache_test.exs

@@ -1,6 +1,8 @@
 defmodule Phoenix.ReactServer.CacheTest do
   use ExUnit.Case, async: true
 
+  @moduletag :unit
+
   alias Phoenix.ReactServer.Cache
 
   setup_all do

test/phoenix/react_server/helper_test.exs

@@ -1,6 +1,8 @@
 defmodule Phoenix.ReactServer.HelperTest do
   use ExUnit.Case, async: false
 
+  @moduletag :requires_runtime
+
   alias Phoenix.ReactServer.Helper
 
   setup_all do

test/phoenix/react_server/runtime/common_test.exs

@@ -1,6 +1,8 @@
 defmodule Phoenix.ReactServer.Runtime.CommonTest do
   use ExUnit.Case, async: true
 
+  @moduletag :unit
+
   alias Phoenix.ReactServer.Runtime.Common
 
   describe "handle_result/1" do

test/phoenix/react_server/runtime/deno_integration_test.exs

@@ -1,6 +1,8 @@
 defmodule Phoenix.ReactServer.Runtime.DenoIntegrationTest do
   use ExUnit.Case, async: false
 
+  @moduletag :integration
+
   alias Phoenix.ReactServer.Runtime.Deno
 
   describe "integration tests" do

test/phoenix/react_server/runtime/deno_test.exs

@@ -1,6 +1,8 @@
 defmodule Phoenix.ReactServer.Runtime.DenoTest do
   use ExUnit.Case, async: false
 
+  @moduletag :unit
+
   alias Phoenix.ReactServer.Runtime.Deno
 
   describe "config/0" do

test/phoenix/react_server/runtime/file_watcher_test.exs

@@ -4,6 +4,7 @@ defmodule Phoenix.ReactServer.Runtime.FileWatcherTest do
   alias Phoenix.ReactServer.Runtime.FileWatcher
 
   @moduletag :capture_log
+  @moduletag :integration
 
   setup do
     # Create a temporary directory for testing