Add and apply ConstantDefinitionInBlock rule

This rule was added in Rubocop 0.91.0. A similar rule named
LeakyConstantDeclaration was added in rubocop-rspec 1.34.0.

Note using the FILENAMES constant did not result in an offense using the
ConstantDefinitionInBlock rule but did result in an offense using the
LeakyConstantDeclaration rule. I've simplified the code to get rid of
the constant; not sure why we were adding a constant with `||=` in the
middle of a spec.

.rubocop.yml

@@ -166,6 +166,9 @@ Layout/TrailingWhitespace:
 Lint/AmbiguousRegexpLiteral:
   Enabled: true
 
+Lint/ConstantDefinitionInBlock:
+  Enabled: true
+
 Lint/DuplicateMethods:
   Enabled: true
 

spec/lib/consul_form_builder_spec.rb

@@ -1,10 +1,14 @@
 require "rails_helper"
 
 describe ConsulFormBuilder do
-  class DummyModel
-    include ActiveModel::Model
-    OPTIONS = %w[Good Bad Ugly].freeze
-    attr_accessor :title, :quality
+  before do
+    dummy_model = Class.new do
+      include ActiveModel::Model
+      attr_accessor :title, :quality
+    end
+
+    stub_const("DummyModel", dummy_model)
+    stub_const("DummyModel::OPTIONS", %w[Good Bad Ugly].freeze)
   end
 
   let(:builder) { ConsulFormBuilder.new(:dummy, DummyModel.new, ActionView::Base.new, {}) }

spec/models/statisticable_spec.rb

@@ -1,12 +1,16 @@
 require "rails_helper"
 
 describe Statisticable do
-  class DummyStats
-    include Statisticable
+  before do
+    dummy_stats = Class.new do
+      include Statisticable
 
-    def participants
-      User.all
+      def participants
+        User.all
+      end
     end
+
+    stub_const("DummyStats", dummy_stats)
   end
 
   let(:stats) { DummyStats.new(nil) }

spec/shared/system/nested_documentable.rb

@@ -235,12 +235,11 @@ shared_examples "nested documentable" do |login_as_name, documentable_factory_na
       end
       login_as user_to_login
       visit send(path, arguments)
-      FILENAMES ||= %w[clippy empty logo].freeze
 
       send(fill_resource_method_name) if fill_resource_method_name
 
-      documentable.class.max_documents_allowed.times.zip(FILENAMES).each do |_n, fn|
-        documentable_attach_new_file(Rails.root.join("spec/fixtures/files/#{fn}.pdf"))
+      %w[clippy empty logo].take(documentable.class.max_documents_allowed).each do |filename|
+        documentable_attach_new_file(Rails.root.join("spec/fixtures/files/#{filename}.pdf"))
       end
 
       click_on submit_button

spec/views/shared/errors_spec.rb

@@ -1,13 +1,17 @@
 require "rails_helper"
 
 describe "shared errors" do
-  class DummyModel
-    include ActiveModel::Model
-    attr_accessor :title, :description, :days
+  before do
+    dummy_model = Class.new do
+      include ActiveModel::Model
+      attr_accessor :title, :description, :days
 
-    validates :title, presence: true
-    validates :description, presence: true, length: { in: 10..100 }
-    validates :days, numericality: { greater_than: 10 }
+      validates :title, presence: true
+      validates :description, presence: true, length: { in: 10..100 }
+      validates :days, numericality: { greater_than: 10 }
+    end
+
+    stub_const("DummyModel", dummy_model)
   end
 
   it "counts the number of fields with errors" do