Remove feature envy smell from ROM::Mapping#build_relation

config/reek.yml

@@ -20,8 +20,6 @@ DuplicateMethodCall:
   max_calls: 1
 FeatureEnvy:
   enabled: true
-  exclude:
-    - 'ROM::Mapping#build_relation'
 IrresponsibleModule:
   enabled: true
   exclude: []

lib/rom/mapping.rb

@@ -72,8 +72,7 @@ def method_missing(name, *, &block)
     #
     # @api private
     def build_relation(relation, &block)
-      definition = Definition.build(relation.header, &block)
-      environment[relation.name] = Relation.build(relation, definition.mapper)
+      environment[relation.name] = Relation.build_from(relation, &block)
     end
 
   end # Mapping

lib/rom/relation.rb

@@ -58,6 +58,18 @@ def self.build(relation, mapper)
       new(mapper.call(relation), mapper)
     end
 
+    # Build a new relation from a given relation
+    #
+    # @param [Axiom::Relation]
+    #
+    # @return [Relation]
+    #
+    # @api publi
+    def self.build_from(relation, &block)
+      definition = Mapping::Definition.build(relation.header, &block)
+      Relation.build(relation, definition.mapper)
+    end
+
     # Iterate over tuples yielded by the wrapped relation
     #
     # @example