Fix zeitwerk teardown in test suite

This is using a private interface that changed in 2.6

We probably want to support older versions for a while, so I'm
supporting both.

Author: alassek

spec/integration/container/auto_registration/component_dir_namespaces/autoloading_loader_spec.rb

@@ -4,6 +4,8 @@
 require "zeitwerk"
 
 RSpec.describe "Component dir namespaces / Autoloading loader" do
+  include ZeitwerkHelpers
+
   let(:container) {
     root = @dir
     dir_config = defined?(component_dir_config) ? component_dir_config : -> * {}
@@ -21,15 +23,7 @@
 
   let(:loader) { Zeitwerk::Loader.new }
 
-  after do
-    Zeitwerk::Registry.loaders.each(&:unload)
-
-    Zeitwerk::Registry.loaders.clear
-    Zeitwerk::Registry.loaders_managing_gems.clear
-
-    Zeitwerk::ExplicitNamespace.cpaths.clear
-    Zeitwerk::ExplicitNamespace.tracer.disable
-  end
+  after { teardown_zeitwerk }
 
   context "top-level constant namespace" do
     let(:component_dir_config) {

spec/support/zeitwerk_helpers.rb

@@ -7,7 +7,15 @@ def teardown_zeitwerk
     Zeitwerk::Registry.loaders.each(&:unload)
 
     Zeitwerk::Registry.loaders.clear
-    Zeitwerk::Registry.loaders_managing_gems.clear
+
+    # This private interface changes between 2.5.4 and 2.6.0
+    if Zeitwerk::Registry.respond_to?(:loaders_managing_gems)
+      Zeitwerk::Registry.loaders_managing_gems.clear
+    else
+      Zeitwerk::Registry.gem_loaders_by_root_file.clear
+      Zeitwerk::Registry.autoloads.clear
+      Zeitwerk::Registry.inceptions.clear
+    end
 
     Zeitwerk::ExplicitNamespace.cpaths.clear
     Zeitwerk::ExplicitNamespace.tracer.disable