Extract methods for checking for on_* blocks and their contents

- The same code to do the same thing was getting a bit repetitive in
  `Cask/StanzaOrder`, `Cask/StanzaGrouping` and `Cask/NoOverrides`
  cops.

Library/Homebrew/rubocops/cask/mixin/cask_help.rb

@@ -22,6 +22,16 @@ module RuboCop
           cask_block = RuboCop::Cask::AST::CaskBlock.new(block_node, comments)
           on_cask(cask_block)
         end
+
+        def on_system_methods(cask_stanzas)
+          cask_stanzas.select { |s| RuboCop::Cask::Constants::ON_SYSTEM_METHODS.include?(s.stanza_name) }
+        end
+
+        def inner_stanzas(block_node, comments)
+          block_contents = block_node.child_nodes.select(&:begin_type?)
+          inner_nodes = block_contents.map(&:child_nodes).flatten.select(&:send_type?)
+          inner_nodes.map { |n| RuboCop::Cask::AST::Stanza.new(n, comments) }
+        end
       end
     end
   end

Library/Homebrew/rubocops/cask/no_overrides.rb

@@ -7,7 +7,6 @@ module RuboCop
       class NoOverrides < Base
         include CaskHelp
 
-        ON_SYSTEM_METHODS = RuboCop::Cask::Constants::ON_SYSTEM_METHODS
         # These stanzas can be overridden by `on_*` blocks, so take them into account.
         # TODO: Update this list if new stanzas are added to `Cask::DSL` that call `set_unique_stanza`.
         OVERRIDEABLE_METHODS = [
@@ -22,8 +21,7 @@ module RuboCop
         def on_cask(cask_block)
           cask_stanzas = cask_block.toplevel_stanzas
 
-          # Skip if there are no `on_*` blocks.
-          return if (on_blocks = cask_stanzas.select { |s| ON_SYSTEM_METHODS.include?(s.stanza_name) }).none?
+          return unless (on_blocks = on_system_methods(cask_stanzas)).any?
 
           stanzas_in_blocks = on_system_stanzas(on_blocks)
 
@@ -40,9 +38,7 @@ module RuboCop
         def on_system_stanzas(on_system)
           names = Set.new
           method_nodes = on_system.map(&:method_node)
-          method_nodes.each do |node|
-            next unless node.block_type?
-
+          method_nodes.select(&:block_type?).each do |node|
             node.child_nodes.each do |child|
               child.each_node(:send) do |send_node|
                 # Skip (nested) livecheck blocks as its `url` is different to a download `url`.
@@ -51,7 +47,7 @@ module RuboCop
                 if send_node.ancestors.drop_while { |a| !a.begin_type? }.any? { |a| a.dstr_type? || a.regexp_type? }
                   next
                 end
-                next if ON_SYSTEM_METHODS.include?(send_node.method_name)
+                next if RuboCop::Cask::Constants::ON_SYSTEM_METHODS.include?(send_node.method_name)
 
                 names.add(send_node.method_name)
               end

Library/Homebrew/rubocops/cask/stanza_grouping.rb

@@ -6,7 +6,7 @@ require "forwardable"
 module RuboCop
   module Cop
     module Cask
-      # This cop checks that a cask's stanzas are grouped correctly.
+      # This cop checks that a cask's stanzas are grouped correctly, including nested within `on_*` blocks.
       # @see https://docs.brew.sh/Cask-Cookbook#stanza-order
       class StanzaGrouping < Base
         extend Forwardable
@@ -14,7 +14,6 @@ module RuboCop
         include CaskHelp
         include RangeHelp
 
-        ON_SYSTEM_METHODS = RuboCop::Cask::Constants::ON_SYSTEM_METHODS
         MISSING_LINE_MSG = "stanza groups should be separated by a single empty line"
         EXTRA_LINE_MSG = "stanzas within the same group should have no lines between them"
 
@@ -24,17 +23,11 @@ module RuboCop
           cask_stanzas = cask_block.toplevel_stanzas
           add_offenses(cask_stanzas)
 
-          # If present, check grouping of stanzas within `on_*` blocks.
-          return if (on_blocks = cask_stanzas.select { |s| ON_SYSTEM_METHODS.include?(s.stanza_name) }).none?
+          return unless (on_blocks = on_system_methods(cask_stanzas)).any?
 
-          on_blocks.map(&:method_node).each do |on_block|
-            next unless on_block.block_type?
-
-            block_contents = on_block.child_nodes.select(&:begin_type?)
-            inner_nodes = block_contents.map(&:child_nodes).flatten.select(&:send_type?)
-            inner_stanzas = inner_nodes.map { |node| RuboCop::Cask::AST::Stanza.new(node, processed_source.comments) }
-
-            add_offenses(inner_stanzas)
+          on_blocks.map(&:method_node).select(&:block_type?).each do |on_block|
+            stanzas = inner_stanzas(on_block, processed_source.comments)
+            add_offenses(stanzas)
           end
         end
 

Library/Homebrew/rubocops/cask/stanza_order.rb

@@ -6,29 +6,24 @@ require "forwardable"
 module RuboCop
   module Cop
     module Cask
-      # This cop checks that a cask's stanzas are ordered correctly.
+      # This cop checks that a cask's stanzas are ordered correctly, including nested within `on_*` blocks.
       # @see https://docs.brew.sh/Cask-Cookbook#stanza-order
       class StanzaOrder < Base
         extend Forwardable
         extend AutoCorrector
         include CaskHelp
 
-        ON_SYSTEM_METHODS = RuboCop::Cask::Constants::ON_SYSTEM_METHODS
         MESSAGE = "`%<stanza>s` stanza out of order"
 
         def on_cask(cask_block)
           @cask_block = cask_block
           add_offenses(toplevel_stanzas)
 
-          return unless (on_blocks = toplevel_stanzas.select { |s| ON_SYSTEM_METHODS.include?(s.stanza_name) }).any?
+          return unless (on_blocks = on_system_methods(toplevel_stanzas)).any?
 
-          on_blocks.map(&:method_node).each do |on_block|
-            next unless on_block.block_type?
-
-            block_contents = on_block.child_nodes.select(&:begin_type?)
-            inner_nodes = block_contents.map(&:child_nodes).flatten.select(&:send_type?)
-            inner_stanzas = inner_nodes.map { |node| RuboCop::Cask::AST::Stanza.new(node, processed_source.comments) }
-            add_offenses(inner_stanzas, inner: true)
+          on_blocks.map(&:method_node).select(&:block_type?).each do |on_block|
+            stanzas = inner_stanzas(on_block, processed_source.comments)
+            add_offenses(stanzas, inner: true)
           end
         end