Compute file path with ActiveSupport Inflector if defined

lib/rubocop/cop/rspec/file_path.rb

@@ -130,6 +130,13 @@ def expected_path(constant)
         end
 
         def camel_to_snake_case(string)
+          if defined?(ActiveSupport::Inflector)
+            if File.exist?('./config/initializers/inflections.rb')
+              require './config/initializers/inflections'
+            end
+            return ActiveSupport::Inflector.underscore(string)
+          end
+
           string
             .gsub(/([^A-Z])([A-Z]+)/, '\1_\2')
             .gsub(/([A-Z])([A-Z][^A-Z\d]+)/, '\1_\2')

rubocop-rspec.gemspec

@@ -39,6 +39,7 @@ Gem::Specification.new do |spec|
 
   spec.add_runtime_dependency 'rubocop', '~> 1.19'
 
+  spec.add_development_dependency 'activesupport'
   spec.add_development_dependency 'rack'
   spec.add_development_dependency 'rake'
   spec.add_development_dependency 'rspec', '>= 3.4'

spec/rubocop/cop/rspec/file_path_spec.rb

@@ -246,6 +246,27 @@ class Foo
     end
   end
 
+  context 'when ActiveSupport is defined' do
+    before { require 'active_support/inflector' }
+
+    it 'registers an offense for a bad path when there is no custom acronym' do
+      expect_offense(<<-RUBY, 'pvp_class_foo_spec.rb')
+        describe PvPClass, 'foo' do; end
+        ^^^^^^^^^^^^^^^^^^^^^^^^ Spec path should end with `pv_p_class*foo*_spec.rb`.
+      RUBY
+    end
+
+    it 'does not register an offense when class name contains custom acronym' do
+      ActiveSupport::Inflector.inflections do |inflect|
+        inflect.acronym('PvP')
+      end
+
+      expect_no_offenses(<<-RUBY, 'pvp_class_foo_spec.rb')
+        describe PvPClass, 'foo' do; end
+      RUBY
+    end
+  end
+
   context 'when configured with IgnoreMethods' do
     let(:cop_config) { { 'IgnoreMethods' => true } }