Add a separate test run for testing code-reloading

simplecov is incompatible with code
reloads (simplecov-ruby/simplecov#389), so
trying to add `cache_classes = false` to our regular test runs results
in broken coverage reports.

.github/workflows/ci.yml

@@ -71,10 +71,12 @@ jobs:
       run: |
         bundle config path vendor/bundle
         bundle update
-        bundle exec rake test spec
+        # Code-reloading isn't compatible with simplecov, so we need to run once
+        # to collect coverage, and again to test reloads.
+        MEASURE_COVERAGE=true bundle exec rake test spec
+        ENABLE_RELOADING=true bundle exec rake test spec
       env:
         RAISE_ON_WARNING: 1
-        MEASURE_COVERAGE: true
         RAILS_VERSION: ${{ matrix.rails_version }}
         CAPTURE_PATCH_ENABLED: ${{ matrix.mode == 'capture_patch_enabled' && 'true' || 'false' }}
     - name: Upload coverage results

test/sandbox/config/environments/test.rb

@@ -8,8 +8,9 @@
   # your test database is "scratch space" for the test suite and is wiped
   # and recreated between test runs.  Don't rely on the data there!
 
-  # `cache_classes=false` is necessary to test code-reloading for people using VC in development
-  config.cache_classes = false
+  # `cache_classes=false` is necessary to test code-reloading for people using VC in development.
+  # However, it's incompatible with collecting simplecov coverage reports.
+  config.cache_classes = !ENV["ENABLE_RELOADING"]
 
   # Show full error reports and disable caching
   config.consider_all_requests_local = true

test/sandbox/test/integration_test.rb

@@ -128,6 +128,8 @@ def test_inherited_component_with_call_method_does_not_recompile_superclass
   end
 
   def test_helper_changes_are_reflected_on_new_request
+    skip if Rails.application.config.cache_classes
+
     get "/helpers_proxy_component"
     assert_select("div", "Hello helper method")
     assert_response :success
@@ -151,6 +153,8 @@ def message
   end
 
   def test_helper_changes_are_reflected_on_new_request_with_previews
+    skip if Rails.application.config.cache_classes
+
     with_preview_route("/previews") do
       get "/previews/helpers_proxy_component/default"
       assert_select("div", "Hello helper method")

test/sandbox/test/rendering_test.rb

@@ -417,14 +417,18 @@ def test_validations_component
   end
 
   def test_compiles_unrendered_component
-    skip "this might not still be compiled if it's been reloaded since boot"
+    # The UnreferencedComponent will get compiled at boot,
+    # but that might have been thrown away if code-reloading is enabled
+    skip unless Rails.env.cache_classes?
+
     assert UnreferencedComponent.compiled?
-    # Or a possible alternative is booting a fresh process:
-    # assert_equal "true\n", `ruby -r bundler/setup -r ./test/sandbox/config/environment.rb -e "puts UnreferencedComponent.compiled?"`
   end
 
   def test_compiles_components_without_initializers
-    MissingInitializerComponent.compile
+    # MissingInitializerComponent will get compiled at boot,
+    # but that might have been thrown away if code-reloading is enabled
+    skip unless Rails.env.cache_classes?
+
     assert MissingInitializerComponent.compiled?
   end