Refactor old spelling deprecation

Makes rubocop happy, if not me...

Author: ellnix

lib/meilisearch.rb

@@ -16,43 +16,52 @@ module Meilisearch
 end
 
 module MeiliSearch
-  # Softly deprecate the old spelling of the top level module
-  # from MeiliSearch to Meilisearch
-  def self.const_missing(const_name)
-    return super if @warned
-
-    Meilisearch::Utils.logger.warn <<~RENAMED_MODULE_WARNING
-      [meilisearch-ruby] The top-level module of Meilisearch has been renamed.
-      [meilisearch-ruby] Please update "MeiliSearch" to "Meilisearch".
-    RENAMED_MODULE_WARNING
-
-    Meilisearch.constants.each do |constant|
-      const_set(constant, Meilisearch.const_get(constant))
+  class << self
+    # Softly deprecate the old spelling of the top level module
+    # from MeiliSearch to Meilisearch
+    def const_missing(const_name)
+      return super if @warned
+
+      _warn_about_deprecation
+      _define_constants
+
+      @warned = true
+
+      # Now that all the proper constants have been set,
+      # we can tell ruby to search for the const in MeiliSearch again.
+      # If it's still not found, then it does not exist in
+      # Meilisearch and the call to `super` will throw a normal error
+      const_get(const_name)
     end
 
-    @warned = true
+    def method_missing(method_name)
+      unless @warned
+        _warn_about_deprecation
+        _define_constants
+      end
 
-    # Now that all the proper constants have been set,
-    # we can tell ruby to search for the const in MeiliSearch again.
-    # If it's still not found, then it does not exist in
-    # Meilisearch and the call to `super` will throw a normal error
-    const_get(const_name)
-  end
+      @warned = true
+
+      Meilisearch.send(method_name)
+    end
 
-  def self.method_missing(method_name)
-    unless @warned
+    def respond_to_missing?(method_name, *)
+      Meilisearch.respond_to?(method_name) || super
+    end
+
+    private
+
+    def _warn_about_deprecation
       Meilisearch::Utils.logger.warn <<~RENAMED_MODULE_WARNING
         [meilisearch-ruby] The top-level module of Meilisearch has been renamed.
         [meilisearch-ruby] Please update "MeiliSearch" to "Meilisearch".
       RENAMED_MODULE_WARNING
+    end
 
+    def _define_constants
       Meilisearch.constants.each do |constant|
         const_set(constant, Meilisearch.const_get(constant))
       end
     end
-
-    @warned = true
-
-    Meilisearch.send(method_name)
   end
 end