Allow setting different namespace root

lib/im/error.rb

@@ -19,6 +19,9 @@ def initialize
     end
   end
 
+  class SetupFinished < Error
+  end
+
   class InvalidModuleName < Error
   end
 end

lib/im/kernel.rb

@@ -18,7 +18,11 @@ def require(path)
         if loaded = !$LOADED_FEATURES.include?(feature_path)
           $LOADED_FEATURES << feature_path
           begin
-            load path, loader
+            if loader.root == Object
+              load path
+            else
+              load path, loader.root
+            end
           rescue => e
             $LOADED_FEATURES.delete(feature_path)
             raise e

lib/im/loader.rb

@@ -113,7 +113,11 @@ def pretty_print(q)
     # @sig Mutex
     attr_reader :mutex2
 
-    def initialize
+    # @private
+    # @sig Module
+    attr_reader :root
+
+    def initialize(root: self)
       super
 
       @module_prefix   = "#{Im.cpath(self)}::"
@@ -125,13 +129,19 @@ def initialize
       @module_cpaths   = {}
       @mutex           = Mutex.new
       @mutex2          = Mutex.new
+      @root            = root
       @setup           = false
       @eager_loaded    = false
 
       Registry.register_loader(self)
       Registry.register_autoloaded_module(get_object_hash(self), nil, self)
     end
 
+    def root=(root)
+      raise SetupFinished, "cannot set root after setup" if @setup
+      @root = root
+    end
+
     # Sets autoloads in the root namespaces.
     #
     # @sig () -> void
@@ -351,7 +361,7 @@ def all_dirs
     private # -------------------------------------------------------------------------------------
 
     # @sig (String, Module?) -> void
-    def set_autoloads_in_dir(dir, parent = self)
+    def set_autoloads_in_dir(dir, parent = root)
       ls(dir) do |basename, abspath|
         begin
           if ruby?(basename)
@@ -517,15 +527,15 @@ def raise_if_conflicting_directory(dir)
 
     # @sig (Module, Symbol) -> String
     def relative_cpath(parent, cname)
-      if self == parent
+      if root == parent
         cname.to_s
       elsif module_cpaths.key?(get_object_hash(parent))
         "#{module_cpaths[get_object_hash(parent)]}::#{cname}"
       else
         # If an autoloaded file loads an autoloaded constant from another file, we need to deduce the module name
         # before we can add the parent to module_cpaths. In this case, we have no choice but to work from to_s.
         mod_name = Im.cpath(parent)
-        current_module_prefix = "#{Im.cpath(self)}::"
+        current_module_prefix = "#{Im.cpath(root)}::"
         raise InvalidModuleName, "invalid module name for #{parent}" unless mod_name.start_with?(current_module_prefix)
         "#{mod_name}::#{cname}".delete_prefix!(current_module_prefix)
       end

lib/im/loader/config.rb

@@ -81,7 +81,7 @@ module Im::Loader::Config
   attr_reader :on_unload_callbacks
   private :on_unload_callbacks
 
-  def initialize
+  def initialize(root: self)
     @inflector              = Im::Inflector.new
     @logger                 = self.class.default_logger
     @tag                    = SecureRandom.hex(3)

test/lib/im/test_different_root.rb

@@ -0,0 +1,26 @@
+require "test_helper"
+
+class TestDifferentRoot < LoaderTest
+  test "setting a different root for loader" do
+    files = [["foo.rb", "module Foo; end"]]
+
+    mod = Module.new
+    @loader = new_loader(root: mod, setup: false)
+
+    with_setup(files) do
+      assert mod::Foo
+    end
+  end
+
+  test "setting Object as root" do
+    on_teardown { remove_const :Foo, from: Object }
+
+    files = [["foo.rb", "module Foo; end"]]
+
+    @loader = new_loader(root: Object, setup: false)
+
+    with_setup(files) do
+      assert ::Foo
+    end
+  end
+end

test/support/loader_test.rb

@@ -9,10 +9,11 @@ def setup
     @loader = new_loader(setup: false)
   end
 
-  def new_loader(dirs: [], enable_reloading: true, setup: true)
+  def new_loader(dirs: [], enable_reloading: true, setup: true, root: nil)
     Im::Loader.new.tap do |loader|
       Array(dirs).each { |dir| loader.push_dir(dir) }
       loader.enable_reloading if enable_reloading
+      loader.root = root      if root
       loader.setup            if setup
     end
   end