Add and apply ShadowingOuterLocalVariable rule

Naming two variables the same way is confusing at the very least, and
can lead to hard to debug errors. That's why the Ruby interpreter issues
a warning when we do so.

.rubocop_basic.yml

@@ -120,6 +120,9 @@ Layout/TrailingWhitespace:
 Lint/LiteralAsCondition:
   Enabled: true
 
+Lint/ShadowingOuterLocalVariable:
+  Enabled: true
+
 Lint/UselessAssignment:
   Enabled: true
 

app/controllers/tracking/budget_investments_controller.rb

@@ -58,14 +58,13 @@ class Tracking::BudgetInvestmentsController < Tracking::BaseController
                               }
                             ]
 
-      filters = investment_headings.inject(all_headings_filter) do |filters, heading|
+      investment_headings.inject(all_headings_filter) do |filters, heading|
         filters << {
           name: heading.name,
           id: heading.id,
           count: investments.select { |i| i.heading_id == heading.id }.size
         }
-      end
-      filters.uniq
+      end.uniq
     end
 
     def restrict_access_to_assigned_items

db/dev_seeds/polls.rb

@@ -222,10 +222,10 @@ section "Creating Poll Questions from Proposals" do
     poll = Poll.current.first
     question = Poll::Question.new(poll: poll)
     question.copy_attributes_from_proposal(proposal)
-    title = question.title
+    question_title = question.title
     I18n.available_locales.map do |locale|
       Globalize.with_locale(locale) do
-        question.title = "#{title} (#{locale})"
+        question.title = "#{question_title} (#{locale})"
       end
     end
     question.save!
@@ -252,10 +252,10 @@ section "Creating Successful Proposals" do
     poll = Poll.current.first
     question = Poll::Question.new(poll: poll)
     question.copy_attributes_from_proposal(proposal)
-    title = question.title
+    question_title = question.title
     I18n.available_locales.map do |locale|
       Globalize.with_locale(locale) do
-        question.title = "#{title} (#{locale})"
+        question.title = "#{question_title} (#{locale})"
       end
     end
     question.save!

spec/features/admin/budget_investments_spec.rb

@@ -1773,8 +1773,8 @@ describe "Admin budget investments" do
       visit admin_budget_budget_investments_path(budget)
 
       cookies = page.driver.browser.manage.all_cookies
-      cookie = cookies.find { |cookie| cookie[:name] == "investments-columns" }
-      cookie_value = cookie[:value]
+      columns_cookie = cookies.find { |cookie| cookie[:name] == "investments-columns" }
+      cookie_value = columns_cookie[:value]
 
       expect(cookie_value).to eq("id,title,supports,admin,valuator,geozone," +
         "feasibility,price,valuation_finished,visible_to_valuators,selected,incompatible")
@@ -1827,8 +1827,8 @@ describe "Admin budget investments" do
       end
 
       cookies = page.driver.browser.manage.all_cookies
-      cookie = cookies.find { |cookie| cookie[:name] == "investments-columns" }
-      cookie_value = cookie[:value]
+      columns_cookie = cookies.find { |cookie| cookie[:name] == "investments-columns" }
+      cookie_value = columns_cookie[:value]
 
       expect(cookie_value).to eq("id,supports,admin,geozone," +
         "feasibility,valuation_finished,visible_to_valuators,selected,incompatible,author")
@@ -1836,8 +1836,8 @@ describe "Admin budget investments" do
       visit admin_budget_budget_investments_path(budget)
 
       cookies = page.driver.browser.manage.all_cookies
-      cookie = cookies.find { |cookie| cookie[:name] == "investments-columns" }
-      cookie_value = cookie[:value]
+      columns_cookie = cookies.find { |cookie| cookie[:name] == "investments-columns" }
+      cookie_value = columns_cookie[:value]
 
       expect(cookie_value).to eq("id,supports,admin,geozone,feasibility,valuation_finished," +
         "visible_to_valuators,selected,incompatible,author")