Add tests for ReloadableRequire

Add integration tests covering:
- require and require_relative with nested dependencies
- autoload with nested require
- reload command behavior
- $LOADED_FEATURES and $LOAD_PATH consistency

Author: ahogappa

test/irb/test_reloadable_require.rb

@@ -0,0 +1,294 @@
+# frozen_string_literal: true
+
+require "tempfile"
+require "fileutils"
+
+require_relative "helper"
+
+module TestIRB
+  class ReloadableRequireIntegrationTest < IntegrationTestCase
+    def setup
+      super
+
+      omit "ReloadableRequire requires Ruby::Box" if !defined?(Ruby::Box) || !Ruby::Box.enabled?
+
+      @envs["RUBY_BOX"] = "1"
+
+      setup_lib_files
+
+      write_rc <<~RUBY
+        IRB.conf[:RELOADABLE_REQUIRE] = true
+        $LOAD_PATH.unshift('#{@lib_dir}')
+      RUBY
+    end
+
+    def teardown
+      super
+      FileUtils.rm_rf(@lib_dir) if @lib_dir
+      @pwd_files&.each { |f| File.delete(f) if File.exist?(f) }
+    end
+
+    def test_require_enables_reload
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "require 'nested_a'"
+        type "NESTED_A_VALUE"
+        type "NESTED_B_VALUE"
+        type "reload"
+        type "exit!"
+      end
+
+      assert_include output, "=> \"from_a\""
+      assert_include output, "=> \"from_b\""
+      assert_include output, "Reloaded: #{@nested_a_path}"
+      assert_include output, "Reloaded: #{@nested_b_path}"
+    end
+
+    def test_require_relative_from_irb_prompt_enables_reload
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "require_relative 'require_relative_lib'"
+        type "REQUIRE_RELATIVE_LIB_VALUE"
+        type "REQUIRE_RELATIVE_DEP"
+        type "reload"
+        type "exit!"
+      end
+
+      assert_include output, "=> 42"
+      assert_include output, "=> \"dep\""
+      assert_include output, "Reloaded: #{@require_relative_lib_path}"
+      assert_include output, "Reloaded: #{@require_relative_dep_path}"
+    end
+
+    def test_require_with_nested_require_relative_enables_reload
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "require '#{@relative_nested_a_path}'"
+        type "RELATIVE_NESTED_A"
+        type "RELATIVE_NESTED_B"
+        type "reload"
+        type "exit!"
+      end
+
+      assert_include output, "=> \"from_a\""
+      assert_include output, "=> \"from_b\""
+      assert_include output, "Reloaded: #{@relative_nested_a_path}"
+      assert_include output, "Reloaded: #{@relative_nested_b_path}"
+    end
+
+    def test_autoload_enables_reload
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "autoload :AutoloadMain, 'autoload_main'"
+        type "AutoloadMain::VALUE"
+        type "AUTOLOAD_DEP_VALUE"
+        type "reload"
+        type "exit!"
+      end
+
+      assert_include output, "=> \"main\""
+      assert_include output, "=> \"dependency\""
+      assert_include output, "Reloaded: #{@autoload_main_path}"
+      assert_include output, "Reloaded: #{@autoload_dep_path}"
+    end
+
+    def test_reload_without_any_loaded_files
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "reload"
+        type "exit!"
+      end
+
+      assert_include output, "No files to reload"
+    end
+
+    def test_reload_reflects_file_changes
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "require '#{@changeable_lib_path}'"
+        type "CHANGEABLE_VALUE"
+        type "File.write('#{@changeable_lib_path}', \"CHANGEABLE_VALUE = 'modified'\\n\")"
+        type "reload"
+        type "CHANGEABLE_VALUE"
+        type "exit!"
+      end
+
+      assert_include output, "=> \"original\""
+      assert_include output, "Reloaded: #{@changeable_lib_path}"
+      assert_include output, "=> \"modified\""
+    end
+
+    def test_reload_command_without_reloadable_require_enabled
+      write_rc <<~'RUBY'
+        IRB.conf[:RELOADABLE_REQUIRE] = false
+      RUBY
+
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "reload"
+        type "exit!"
+      end
+
+      assert_include output, "requires IRB.conf[:RELOADABLE_REQUIRE] = true"
+    end
+
+    def test_require_updates_loaded_features
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "require 'nested_a'"
+        type "$LOADED_FEATURES.include?('#{@nested_a_path}')"
+        type "$LOADED_FEATURES.include?('#{@nested_b_path}')"
+        type "exit!"
+      end
+
+      # Both files should be in $LOADED_FEATURES
+      assert_equal 2, output.scan("=> true").count
+    end
+
+    def test_autoload_updates_loaded_features
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "autoload :AutoloadMain, 'autoload_main'"
+        type "AutoloadMain"
+        type "$LOADED_FEATURES.include?('#{@autoload_main_path}')"
+        type "$LOADED_FEATURES.include?('#{@autoload_dep_path}')"
+        type "exit!"
+      end
+
+      # Both files should be in $LOADED_FEATURES
+      assert_equal 2, output.scan("=> true").count
+    end
+
+    def test_reload_preserves_loaded_features
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "require 'nested_a'"
+        type "$LOADED_FEATURES.include?('#{@nested_a_path}')"
+        type "reload"
+        type "$LOADED_FEATURES.include?('#{@nested_a_path}')"
+        type "exit!"
+      end
+
+      # Both checks should return true (before and after reload)
+      assert_equal 2, output.scan("=> true").count
+    end
+
+    def test_require_does_not_modify_load_path
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "load_path_before = $LOAD_PATH.dup"
+        type "require 'nested_a'"
+        type "$LOAD_PATH == load_path_before"
+        type "exit!"
+      end
+
+      assert_include output, "=> true"
+    end
+
+    private
+
+    def setup_lib_files
+      @lib_dir = Dir.mktmpdir
+      @pwd_files = []
+
+      # Nested require files (primary test files)
+      @nested_b_path = create_lib_file("nested_b.rb", "NESTED_B_VALUE = 'from_b'\n")
+      @nested_a_path = create_lib_file("nested_a.rb", "require 'nested_b'\nNESTED_A_VALUE = 'from_a'\n")
+
+      # Nested require_relative files (for testing require that internally uses require_relative)
+      @relative_nested_b_path = create_lib_file("relative_nested_b.rb", "RELATIVE_NESTED_B = 'from_b'\n")
+      @relative_nested_a_path = create_lib_file(
+        "relative_nested_a.rb",
+        "require_relative 'relative_nested_b'\nRELATIVE_NESTED_A = 'from_a'\n"
+      )
+
+      # Files in Dir.pwd for require_relative from IRB prompt (with nested dependency)
+      @require_relative_dep_path = create_pwd_file("require_relative_dep.rb", "REQUIRE_RELATIVE_DEP = 'dep'\n")
+      @require_relative_lib_path = create_pwd_file(
+        "require_relative_lib.rb",
+        "require_relative 'require_relative_dep'\nREQUIRE_RELATIVE_LIB_VALUE = 42\n"
+      )
+
+      # Autoload files with nested require
+      @autoload_dep_path = create_lib_file("autoload_dep.rb", "AUTOLOAD_DEP_VALUE = 'dependency'\n")
+      @autoload_main_path = create_lib_file(
+        "autoload_main.rb",
+        "require 'autoload_dep'\nmodule AutoloadMain; VALUE = 'main'; end\n"
+      )
+
+      # Changeable file (for testing reload reflects changes)
+      @changeable_lib_path = create_lib_file("changeable.rb", "CHANGEABLE_VALUE = 'original'\n")
+    end
+
+    def create_lib_file(name, content)
+      path = File.join(@lib_dir, name)
+      File.write(path, content)
+      File.realpath(path)
+    end
+
+    def create_pwd_file(name, content)
+      path = File.join(Dir.pwd, name)
+      File.write(path, content)
+      @pwd_files << path
+      File.realpath(path)
+    end
+  end
+
+  class ReloadableRequireDisabledTest < IntegrationTestCase
+    def setup
+      super
+
+      omit "This test is for Ruby::Box disabled environment" if defined?(Ruby::Box) && Ruby::Box.enabled?
+    end
+
+    def test_reload_command_shows_error_without_ruby_box
+      write_rc <<~'RUBY'
+        IRB.conf[:RELOADABLE_REQUIRE] = true
+      RUBY
+
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      output = run_ruby_file do
+        type "reload"
+        type "exit!"
+      end
+
+      assert_include output, "requires IRB.conf[:RELOADABLE_REQUIRE] = true and Ruby::Box"
+    end
+  end
+end