diff --git a/.rubocop.yml b/.rubocop.yml
index 2ac81a644f1..4cca4d06f66 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -105,3 +105,6 @@ Documentation:
 
 Encoding:
   Enabled: false # don't require utf-8 encoding on every file
+
+MethodCalledOnDoEndBlock:
+  Enabled: true
diff --git a/app/controllers/activation_keys_controller.rb b/app/controllers/activation_keys_controller.rb
index 799dc97dfcb..767eb2f5997 100644
--- a/app/controllers/activation_keys_controller.rb
+++ b/app/controllers/activation_keys_controller.rb
@@ -346,8 +346,8 @@ def retrieve_all_pools
         next if product.nil?
         pool.provider_id = product.provider_id
         pool
-      end.compact
-      subscriptions = [] if subscriptions.nil?
+      end
+      subscriptions.compact!
     else
       subscriptions = []
     end
diff --git a/app/controllers/api/v1/distributors_controller.rb b/app/controllers/api/v1/distributors_controller.rb
index 1751ab6c214..aefb3920bda 100644
--- a/app/controllers/api/v1/distributors_controller.rb
+++ b/app/controllers/api/v1/distributors_controller.rb
@@ -159,7 +159,8 @@ def report # rubocop:disable MethodLength
           :only    => [:uuid, :name, :location, :created_at, :updated_at],
           :methods => [:environment, :organization, :compliance_color, :compliant_until, :custom_info]
       )
-    end.flatten!
+    end
+    data.flatten!
 
     transforms = lambda do |r|
       r.organization    = r.organization.name
diff --git a/app/controllers/api/v1/systems_controller.rb b/app/controllers/api/v1/systems_controller.rb
index b0e1ec99705..da62a0190db 100644
--- a/app/controllers/api/v1/systems_controller.rb
+++ b/app/controllers/api/v1/systems_controller.rb
@@ -311,7 +311,8 @@ def report # rubocop:disable MethodLength
           :only    => [:uuid, :name, :location, :created_at, :updated_at],
           :methods => [:environment, :organization, :compliance_color, :compliant_until, :custom_info]
       )
-    end.flatten!
+    end
+    data.flatten!
 
     transforms = lambda do |r|
       r.organization    = r.organization.name
diff --git a/app/controllers/consumers_controller_logic.rb b/app/controllers/consumers_controller_logic.rb
index 43e33aae616..c098c3c7bf8 100644
--- a/app/controllers/consumers_controller_logic.rb
+++ b/app/controllers/consumers_controller_logic.rb
@@ -43,8 +43,8 @@ def available_subscriptions(cp_pools, organization = current_organization)
 
         pool.provider_id = product[0].provider_id
         pool
-      end.compact
-      subscriptions = [] if subscriptions.nil?
+      end
+      subscriptions.compact!
     else
       subscriptions = []
     end
diff --git a/app/controllers/content_search_controller.rb b/app/controllers/content_search_controller.rb
index 1e206f6f1c7..40fa64909f8 100644
--- a/app/controllers/content_search_controller.rb
+++ b/app/controllers/content_search_controller.rb
@@ -117,7 +117,8 @@ def packages
 
       prod_rows = product_repo_map.collect do |product, reps|
         spanned_product_content(view, product, reps, 'package', package_ids)
-      end.flatten
+      end
+      prod_rows.flatten!
 
       if !prod_rows.empty?
         rows << view_hash[view.id]
diff --git a/app/helpers/menu.rb b/app/helpers/menu.rb
index a3675bf7735..ed3908f21de 100644
--- a/app/helpers/menu.rb
+++ b/app/helpers/menu.rb
@@ -55,9 +55,10 @@ def render_main_sub_menu
   def render_sublevel_menu(items = nil, prune = true)
     items ||= menu_main
     prune_menu(items) if prune
-    items.collect do |top_level|
+    result = items.collect do |top_level|
       render_navigation(:items => top_level[:items], :expand_all => true) if top_level[:items]
-    end.compact.join("").html_safe
+    end
+    result.compact.join("").html_safe
   end
 
   private
diff --git a/app/lib/authorization_rules.rb b/app/lib/authorization_rules.rb
index de3515dbc6f..d48ee67e74b 100644
--- a/app/lib/authorization_rules.rb
+++ b/app/lib/authorization_rules.rb
@@ -68,7 +68,7 @@ def build_bad_params_error_msg(bad_params, params)
   def check_hash_params(rule, params)
     rule = rule.with_indifferent_access
     params = params.with_indifferent_access
-    rule.keys.collect do |k|
+    result = rule.keys.collect do |k|
       if params[k]
         keys = params[k].keys - rule[k].collect { |r| r.to_s }
         if keys.empty?
@@ -77,7 +77,8 @@ def check_hash_params(rule, params)
           {k => keys}
         end
       end
-    end.compact
+    end
+    result.compact
   end
 
   def check_array_params(rule, params)
diff --git a/app/lib/glue/event.rb b/app/lib/glue/event.rb
index cd25312bd61..fe7a8e63dff 100644
--- a/app/lib/glue/event.rb
+++ b/app/lib/glue/event.rb
@@ -56,7 +56,8 @@ def self.trigger(event_class, *args)
           message << step.error['backtrace'].join("\n")
         end
           message
-      end.join("\n")
+      end
+      log_message = log_message.join("\n")
 
       if execution_plan.failed_steps.any?
         ::Logging.logger['glue'].error(log_message)
diff --git a/app/lib/util/support.rb b/app/lib/util/support.rb
index 08a04da93ba..f8cbeed4db5 100644
--- a/app/lib/util/support.rb
+++ b/app/lib/util/support.rb
@@ -76,7 +76,8 @@ def self.diff_hash_params(rule, params)
             end
           end
         end
-      end.compact.flatten
+      end
+      diff_data = diff_data.compact.flatten
 
       return diff_data unless diff_data.nil? || diff_data.empty?
       stringify(params.keys) - stringify(rule.keys)
diff --git a/app/models/erratum_rule.rb b/app/models/erratum_rule.rb
index 301ff0c946e..bda26e91864 100644
--- a/app/models/erratum_rule.rb
+++ b/app/models/erratum_rule.rb
@@ -65,7 +65,8 @@ def generate_clauses(repo)
       # end.compact.flatten
       ids = parameters[:units].collect do |unit|
         unit[:id]
-      end.compact
+      end
+      ids.compact!
 
       {"id" => {"$in" => ids}}  unless ids.empty?
     else
diff --git a/app/models/glue/provider.rb b/app/models/glue/provider.rb
index b3acceffd1e..178120ad8d2 100644
--- a/app/models/glue/provider.rb
+++ b/app/models/glue/provider.rb
@@ -60,9 +60,10 @@ def refresh_manifest(upstream, options = {})
 
     def sync
       Rails.logger.debug "Syncing provider #{name}"
-      self.products.collect do |p|
+      syncs = self.products.collect do |p|
         p.sync
-      end.flatten
+      end
+      syncs.flatten
     end
 
     def synced?
@@ -71,9 +72,10 @@ def synced?
 
     #get last sync status of all repositories in this provider
     def latest_sync_statuses
-      self.products.collect do |p|
+      statuses = self.products.collect do |p|
         p.latest_sync_statuses
-      end.flatten
+      end
+      statuses.flatten
     end
 
     # Get the most relavant status for all the repos in this Provider
@@ -436,8 +438,8 @@ def index_subscriptions
           next if product.nil?
           pool.provider_id = product.provider_id   # Set so it is saved into elastic search
           pool
-        end.compact
-        subscriptions = [] if subscriptions.nil?
+        end
+        subscriptions.compact!
       else
         subscriptions = []
       end
diff --git a/app/models/glue/pulp/errata.rb b/app/models/glue/pulp/errata.rb
index 79b906ea017..cf9733739a5 100644
--- a/app/models/glue/pulp/errata.rb
+++ b/app/models/glue/pulp/errata.rb
@@ -43,9 +43,10 @@ def self.find_by_errata_id(id)
       def self.list_by_filter_clauses(clauses)
         errata = Katello.pulp_server.extensions.errata.search(::Errata::CONTENT_TYPE, :filters => clauses)
         if errata
-          errata.collect do |attrs|
+          result = errata.collect do |attrs|
             ::Errata.new(attrs) if attrs
-          end.compact
+          end
+          result.compact
         else
           []
         end
@@ -64,11 +65,12 @@ def initialize(params = {}, options = {})
     end
 
     def package_filenames
-      self.pkglist.collect do |pkgs|
+      filenames = self.pkglist.collect do |pkgs|
         pkgs['packages'].collect do |pk|
           pk["filename"]
         end
-      end.flatten
+      end
+      filenames.flatten
     end
 
     def included_packages
diff --git a/app/models/glue/pulp/package_group.rb b/app/models/glue/pulp/package_group.rb
index 2827094cc40..50947c91f06 100644
--- a/app/models/glue/pulp/package_group.rb
+++ b/app/models/glue/pulp/package_group.rb
@@ -44,9 +44,7 @@ def initialize(params = {}, options = {})
       [:default_package_names, :conditional_package_names,
        :optional_package_names, :mandatory_package_names].each do |attr|
         values = send(attr)
-        values = values.collect do |v|
-          v.split(", ")
-        end.flatten
+        values = values.collect { |v| v.split(", ") }.flatten
         send("#{attr}=", values)
       end
 
diff --git a/app/models/glue/pulp/repo.rb b/app/models/glue/pulp/repo.rb
index 710d1dbd909..c04519c77d3 100644
--- a/app/models/glue/pulp/repo.rb
+++ b/app/models/glue/pulp/repo.rb
@@ -266,7 +266,8 @@ def purge_empty_groups_errata
       # Remove all errata with no packages
       errata_to_delete = errata.collect do |erratum|
         erratum.errata_id if filenames.intersection(erratum.package_filenames).empty?
-      end.compact
+      end
+      errata_to_delete.compact!
 
       #do the errata remove call
       unless errata_to_delete.empty?
@@ -276,7 +277,8 @@ def purge_empty_groups_errata
       # Remove all  package groups with no packages
       package_groups_to_delete = package_groups.collect do |group|
         group.package_group_id if rpm_names.intersection(group.package_names).empty?
-      end.compact
+      end
+      package_groups_to_delete.compact!
 
       unless package_groups_to_delete.empty?
         unassociate_by_filter(FilterRule::PACKAGE_GROUP, {"id" => {"$in" => package_groups_to_delete}})
diff --git a/app/models/glue/pulp/repos.rb b/app/models/glue/pulp/repos.rb
index 33ffee36c23..88826d0cdd4 100644
--- a/app/models/glue/pulp/repos.rb
+++ b/app/models/glue/pulp/repos.rb
@@ -109,21 +109,23 @@ def has_package?(id)
     end
 
     def find_packages_by_name(env, name)
-      self.repos(env).collect do |repo|
+      packages = self.repos(env).collect do |repo|
         repo.find_packages_by_name(name).collect do |p|
           p[:repo_id] = repo.id
           p
         end
-      end.flatten(1)
+      end
+      packages.flatten(1)
     end
 
     def find_packages_by_nvre(env, name, version, release, epoch)
-      self.repos(env).collect do |repo|
+      packages = self.repos(env).collect do |repo|
         repo.find_packages_by_nvre(name, version, release, epoch).collect do |p|
           p[:repo_id] = repo.id
           p
         end
-      end.flatten(1)
+      end
+      packages.flatten(1)
     end
 
     def distributions(env)
@@ -136,9 +138,10 @@ def distributions(env)
     end
 
     def get_distribution(env, id)
-      self.repos(env).map do |repo|
+      distribution = self.repos(env).map do |repo|
         repo.distributions.find_all {|d| d.id == id }
-      end.flatten(1)
+      end
+      distribution.flatten(1)
     end
 
     def find_latest_packages_by_name(env, name)
@@ -148,7 +151,8 @@ def find_latest_packages_by_name(env, name)
           pack[:repo_id] = repo.id
           pack
         end
-      end.flatten(1)
+      end
+      packs.flatten!(1)
 
       Util::Package.find_latest_packages packs
     end
@@ -166,9 +170,10 @@ def promoted_to?(target_env)
 
     def sync
       Rails.logger.debug "Syncing product #{self.label}"
-      self.repos(library).collect do |r|
+      repos = self.repos(library).collect do |r|
         r.sync
-      end.flatten
+      end
+      repos.flatten
     end
 
     def synced?
diff --git a/app/models/kt_environment.rb b/app/models/kt_environment.rb
index aba3ab64b29..c07d6e6c9a4 100644
--- a/app/models/kt_environment.rb
+++ b/app/models/kt_environment.rb
@@ -240,21 +240,23 @@ def package_group_categories(search_args = {})
   end
 
   def find_packages_by_name(name)
-    self.products.collect do |prod|
+    products = self.products.collect do |prod|
       prod.find_packages_by_name(self, name).collect do |p|
         p[:product_id] = prod.cp_id
         p
       end
-    end.flatten(1)
+    end
+    products.flatten(1)
   end
 
   def find_packages_by_nvre(name, version, release, epoch)
-    self.products.collect do |prod|
+    products = self.products.collect do |prod|
       prod.find_packages_by_nvre(self, name, version, release, epoch).collect do |p|
         p[:product_id] = prod.cp_id
         p
       end
-    end.flatten(1)
+    end
+    products.flatten(1)
   end
 
   def find_latest_packages_by_name(name)
@@ -264,15 +266,17 @@ def find_latest_packages_by_name(name)
         pack[:product_id] = prod.cp_id
         pack
       end
-    end.flatten(1)
+    end
+    packs.flatten!(1)
 
     Util::Package.find_latest_packages packs
   end
 
   def get_distribution(id)
-    self.products.collect do |prod|
+    distribution = self.products.collect do |prod|
       prod.get_distribution(self, id)
-    end.flatten(1)
+    end
+    distribution.flatten(1)
   end
 
   def unset_users_with_default
diff --git a/app/models/promotion_changeset.rb b/app/models/promotion_changeset.rb
index 930a29485e2..00229884677 100644
--- a/app/models/promotion_changeset.rb
+++ b/app/models/promotion_changeset.rb
@@ -99,9 +99,10 @@ def promote_content(notify = false)
   end
 
   def promote_views(from_env, to_env, views)
-    views.collect do |view|
+    views = views.collect do |view|
       view.promote(from_env, to_env)
-    end.flatten
+    end
+    views.flatten
   end
 
   def update_view_cp_content(to_env)
diff --git a/app/models/task_status.rb b/app/models/task_status.rb
index c1c39a4f107..8423c66e055 100644
--- a/app/models/task_status.rb
+++ b/app/models/task_status.rb
@@ -302,9 +302,10 @@ def rmi_error_description
         stacktrace.split("(").first
       end
     elsif errors =~ /^\[.*,.*\]$/m
-      errors.split(",").map do |error|
+      result = errors.split(",").map do |error|
         error.gsub(/^\W+|\W+$/, "")
-      end.join("\n")
+      end
+      result.join("\n")
     else
       errors
     end
diff --git a/script/check-gettext.rb b/script/check-gettext.rb
index d9aafa38ac7..d26c32c4fb8 100755
--- a/script/check-gettext.rb
+++ b/script/check-gettext.rb
@@ -65,7 +65,8 @@
         end
       end
       [string, suffix]
-    end.compact
+    end
+    gettext_strings.compact
   rescue ArgumentError
     next # we can't scan binary files, skipping
   end