[Fix #4172] Fix false positives in Style/MixinGrouping cop

This cop would register an offense when one of the methods `#include`,
`#extend`, or `#prepend` was sent to an explicit receiver, or used as an
argument to another method.

This change fixes that.

CHANGELOG.md

@@ -7,6 +7,7 @@
 * [#4171](https://github.com/bbatsov/rubocop/pull/4171): Prevent `Rails/Blank` from breaking when RHS of `or` is a naked falsiness check. ([@drenmi][])
 * [#4189](https://github.com/bbatsov/rubocop/pull/4189): Make `Lint/AmbiguousBlockAssociation` aware of lambdas passed as arguments. ([@drenmi][])
 * [#4179](https://github.com/bbatsov/rubocop/pull/4179): Prevent `Rails/Blank` from breaking when LHS of `or` is a naked falsiness check. ([@rrosenblum][])
+* [#4172](https://github.com/bbatsov/rubocop/pull/4172): Fix false positives in `Style/MixinGrouping` cop. ([@drenmi][])
 
 ## 0.48.0 (2017-03-26)
 

lib/rubocop/ast/node/send_node.rb

@@ -6,8 +6,6 @@ module AST
     # node when the builder constructs the AST, making its methods available
     # to all `send` nodes within RuboCop.
     class SendNode < Node
-      MACRO_PARENT_NODES = %i(class module).freeze
-
       # The receiving node of the method invocation.
       #
       # @return [Node, nil] the receiver of the invoked method or `nil`
@@ -38,7 +36,7 @@ def method?(name)
       #
       # @return [Boolean] whether the method is a macro method
       def macro?
-        !receiver && MACRO_PARENT_NODES.include?(parent && parent.type)
+        !receiver && macro_scope?
       end
 
       # Checks whether the method name matches the argument and has an
@@ -185,6 +183,13 @@ def splat_argument?
       def node_parts
         [*self]
       end
+
+      private # rubocop:disable Lint/UselessAccessModifier
+
+      def_matcher :macro_scope?, <<-PATTERN
+        {^({class module} ...)
+         ^^({class module} ... (begin ...))}
+      PATTERN
     end
   end
 end

lib/rubocop/cop/style/mixin_grouping.rb

@@ -41,7 +41,7 @@ class MixinGrouping < Cop
         MSG = 'Put `%s` mixins in %s.'.freeze
 
         def on_send(node)
-          return unless MIXIN_METHODS.include?(node.method_name)
+          return unless node.macro? && MIXIN_METHODS.include?(node.method_name)
 
           check(node)
         end

spec/rubocop/ast/send_node_spec.rb

@@ -88,23 +88,25 @@
   describe '#macro?' do
     context 'without a receiver' do
       context 'when parent is a class' do
-        let(:send_node) { parse_source(source).ast.children[2] }
+        let(:send_node) { parse_source(source).ast.children[2].children[0] }
 
         let(:source) do
           ['class Foo',
            '  bar :baz',
+           '  bar :qux',
            'end'].join("\n")
         end
 
         it { expect(send_node.macro?).to be_truthy }
       end
 
       context 'when parent is a module' do
-        let(:send_node) { parse_source(source).ast.children[1] }
+        let(:send_node) { parse_source(source).ast.children[1].children[0] }
 
         let(:source) do
           ['module Foo',
            '  bar :baz',
+           '  bar :qux',
            'end'].join("\n")
         end
 

spec/rubocop/cop/style/mixin_grouping_spec.rb

@@ -58,6 +58,11 @@
                          '  include Qux',
                          'end'].join("\n")
       end
+
+      context 'when include call is an argument to another method' do
+        it_behaves_like 'code without offense',
+                        'expect(foo).to include(bar, baz)'
+      end
     end
 
     context 'when using `extend`' do
@@ -142,6 +147,12 @@
                          '  include Bar, Qux',
                          'end'].join("\n")
       end
+
+      context 'when include has an explicit receiver' do
+        it_behaves_like 'code without offense',
+                        ['config.include Foo',
+                         'config.include Bar'].join("\n")
+      end
     end
 
     context 'when using `extend`' do