Initial exploration of fallback lookup issue

Co-authored-by: kwerle <23320+kwerle@users.noreply.github.com>

Author: Copilot

test_fallback.rb

@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+require_relative 'spec/test_helper'
+require 'minitest/autorun'
+
+describe 'Fallback behavior' do
+  let(:project_manager) { RubyLanguageServer::ProjectManager.new('/proj', 'file:///foo/') }
+
+  it 'should test current behavior when nothing found in scope' do
+    # Define a class in one file
+    other_file = <<~CODE
+      class MyExternalClass
+        def external_method
+        end
+      end
+    CODE
+    
+    # Reference it from another file where it's not in scope
+    file_text = <<~CODE
+      module SomeModule
+        class SomeClass
+          def some_method
+            MyExternalClass # Exists elsewhere but not in local scope
+          end
+        end
+      end
+    CODE
+
+    project_manager.update_document_content('other_uri', other_file)
+    project_manager.tags_for_uri('other_uri') # Force load
+    
+    project_manager.update_document_content('test_uri', file_text)
+    project_manager.tags_for_uri('test_uri') # Force load
+
+    # Try to find MyExternalClass from test_uri
+    position = OpenStruct.new(line: 3, character: 6)
+    results = project_manager.possible_definitions('test_uri', position)
+    puts "Results for MyExternalClass (should find it globally): #{results.inspect}"
+    puts "Expected to find definition in other_uri"
+  end
+  
+  it 'should test when constant truly does not exist' do
+    file_text = <<~CODE
+      module SomeModule
+        class SomeClass
+          def some_method
+            TotallyNonExistentClass # This truly doesn't exist anywhere
+          end
+        end
+      end
+    CODE
+
+    project_manager.update_document_content('test_uri', file_text)
+    project_manager.tags_for_uri('test_uri') # Force load
+
+    # Try to find non-existent constant
+    position = OpenStruct.new(line: 3, character: 6)
+    results = project_manager.possible_definitions('test_uri', position)
+    puts "Results for TotallyNonExistentClass (shouldn't find anything): #{results.inspect}"
+  end
+end