trace autoloads, and document hints for troubleshooting

Closes #32885.

1 files changed, 49 insertions, 0 deletions

diff --git a/activesupport/test/dependencies_test.rb b/activesupport/test/dependencies_test.rb
index 84cb64a7c2..a486ef5eac 100644
--- a/activesupport/test/dependencies_test.rb
+++ b/activesupport/test/dependencies_test.rb
@@ -1130,3 +1130,52 @@ class DependenciesTest < ActiveSupport::TestCase
     ActiveSupport::Dependencies.hook!
   end
 end
+
+class DependenciesLogging < ActiveSupport::TestCase
+  MESSAGE = "message"
+
+  def with_settings(logger, verbose)
+    original_logger = ActiveSupport::Dependencies.logger
+    original_verbose = ActiveSupport::Dependencies.verbose
+
+    ActiveSupport::Dependencies.logger = logger
+    ActiveSupport::Dependencies.verbose = verbose
+
+    yield
+  ensure
+    ActiveSupport::Dependencies.logger = original_logger
+    ActiveSupport::Dependencies.verbose = original_verbose
+  end
+
+  def fake_logger
+    Class.new do
+      def self.debug(message)
+        message
+      end
+    end
+  end
+
+  test "does not log if the logger is nil and verbose is false" do
+    with_settings(nil, false) do
+      assert_nil ActiveSupport::Dependencies.log(MESSAGE)
+    end
+  end
+
+  test "does not log if the logger is nil and verbose is true" do
+    with_settings(nil, true) do
+      assert_nil ActiveSupport::Dependencies.log(MESSAGE)
+    end
+  end
+
+  test "does not log if the logger is set and verbose is false" do
+    with_settings(fake_logger, false) do
+      assert_nil ActiveSupport::Dependencies.log(MESSAGE)
+    end
+  end
+
+  test "logs if the logger is set and verbose is true" do
+    with_settings(fake_logger, true) do
+      assert_equal "autoloading: #{MESSAGE}", ActiveSupport::Dependencies.log(MESSAGE)
+    end
+  end
+end