Add ProjectPathHelper cop

rubocop/cop/project_path_helper.rb

+module RuboCop
+  module Cop
+    class ProjectPathHelper < RuboCop::Cop::Cop
+      MSG = 'Use short project path helpers without explicitly passing the namespace: ' \
+        '`foo_project_bar_path(project, bar)` instead of ' \
+        '`foo_namespace_project_bar_path(project.namespace, project, bar)`.'.freeze
+
+      METHOD_NAME_PATTERN = /\A([a-z_]+_)?namespace_project(?:_[a-z_]+)?_(?:url|path)\z/.freeze
+
+      def on_send(node)
+        return unless method_name(node).to_s =~ METHOD_NAME_PATTERN
+
+        namespace_expr, project_expr = arguments(node)
+        return unless namespace_expr && project_expr
+
+        return unless namespace_expr.type == :send
+        return unless method_name(namespace_expr) == :namespace
+        return unless receiver(namespace_expr) == project_expr
+
+        add_offense(node, :selector)
+      end
+
+      def autocorrect(node)
+        helper_name = method_name(node).to_s.sub('namespace_project', 'project')
+
+        arguments = arguments(node)
+        arguments.shift # Remove namespace argument
+
+        replacement = "#{helper_name}(#{arguments.map(&:source).join(', ')})"
+
+        lambda do |corrector|
+          corrector.replace(node.source_range, replacement)
+        end
+      end
+
+      private
+
+      def receiver(node)
+        node.children[0]
+      end
+
+      def method_name(node)
+        node.children[1]
+      end
+
+      def arguments(node)
+        node.children[2..-1]
+      end
+    end
+  end
+end

rubocop/rubocop.rb

@@ -3,6 +3,7 @@ require_relative 'cop/gem_fetcher'
 require_relative 'cop/activerecord_serialize'
 require_relative 'cop/redirect_with_status'
 require_relative 'cop/polymorphic_associations'
+require_relative 'cop/project_path_helper'
 require_relative 'cop/migration/add_column'
 require_relative 'cop/migration/add_column_with_default_to_large_table'
 require_relative 'cop/migration/add_concurrent_foreign_key'

spec/rubocop/cop/project_path_helper_spec.rb

+require 'spec_helper'
+
+require 'rubocop'
+require 'rubocop/rspec/support'
+
+require_relative '../../../rubocop/cop/project_path_helper'
+
+describe RuboCop::Cop::ProjectPathHelper do
+  include CopHelper
+
+  subject(:cop) { described_class.new }
+
+  context "when using namespace_project with the project's namespace" do
+    let(:source) { 'edit_namespace_project_issue_path(@issue.project.namespace, @issue.project, @issue)' }
+    let(:correct_source) { 'edit_project_issue_path(@issue.project, @issue)' }
+
+    it 'registers an offense' do
+      inspect_source(cop, source)
+
+      aggregate_failures do
+        expect(cop.offenses.size).to eq(1)
+        expect(cop.offenses.map(&:line)).to eq([1])
+        expect(cop.highlights).to eq(['edit_namespace_project_issue_path'])
+      end
+    end
+
+    it 'autocorrects to the right version' do
+      autocorrected = autocorrect_source(cop, source)
+
+      expect(autocorrected).to eq(correct_source)
+    end
+  end
+
+  context 'when using namespace_project with a different namespace' do
+    it 'registers no offense' do
+      inspect_source(cop, 'edit_namespace_project_issue_path(namespace, project)')
+
+      expect(cop.offenses.size).to eq(0)
+    end
+  end
+end