Add Rake/ClassDefinitionInTask cop

.rubocop.yml

@@ -23,6 +23,12 @@ Style/UnneededPercentQ:
   Exclude:
     - '*.gemspec'
 
+Style/ModuleFunction:
+  Enabled: false
+
+Style/Documentation:
+  Enabled: false
+
 Style/PercentLiteralDelimiters:
   Exclude:
     - '*.gemspec'
@@ -33,4 +39,3 @@ RSpec/ExampleLength:
 Naming/FileName:
   Exclude:
     - 'lib/rubocop-rake.rb'
-

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## master (unreleased)
 
+### New features
+
+* [#6](https://github.com/pocke/rubocop-rake/issues/6): Add `Rake/ClassDefinitionInTask` cop. ([@pocke][])
+
 ### Bug fixes
 
 * [#8](https://github.com/pocke/rubocop-rake/issues/8): Make Rake/Desc to not require description for the default task. ([@pocke][])

config/default.yml

@@ -1,3 +1,8 @@
+Rake/ClassDefinitionInTask:
+  Description: 'Do not define a class or module in rake task, because it will be defined to the top level.'
+  Enabled: true
+  VersionAdded: '0.3.0'
+
 Rake/Desc:
   Description: 'Describe the task with `desc` method.'
   Enabled: true

lib/rubocop-rake.rb

@@ -8,4 +8,6 @@
 
 RuboCop::Rake::Inject.defaults!
 
+require_relative 'rubocop/cop/rake/helper/class_definition'
+require_relative 'rubocop/cop/rake/helper/task_definition'
 require_relative 'rubocop/cop/rake_cops'

lib/rubocop/cop/rake/class_definition_in_task.rb

@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Rake
+      # This cop detects class or module definition in a task or namespace,
+      # because it is defined to the top level.
+      # It is confusing because the scope looks in the task or namespace,
+      # but actually it is defined to the top level.
+      #
+      # @example
+      #   # bad
+      #   task :foo do
+      #     class C
+      #     end
+      #   end
+      #
+      #   # bad
+      #   namespace :foo do
+      #     module M
+      #     end
+      #   end
+      #
+      #   # good - It is also defined to the top level,
+      #   #        but it looks expected behavior.
+      #   class C
+      #   end
+      #   task :foo do
+      #   end
+      #
+      class ClassDefinitionInTask < Cop
+        MSG = 'Do not define a %<type>s in rake task, because it will be defined to the top level.'
+
+        def on_class(node)
+          return if Helper::ClassDefinition.in_class_definition?(node)
+          return unless Helper::TaskDefinition.in_task_or_namespace?(node)
+
+          add_offense(node)
+        end
+
+        def message(node)
+          format(MSG, type: node.type)
+        end
+
+        alias on_module on_class
+      end
+    end
+  end
+end

lib/rubocop/cop/rake/helper/class_definition.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Rake
+      module Helper
+        module ClassDefinition
+          extend NodePattern::Macros
+          extend self
+
+          def_node_matcher :class_definition?, <<~PATTERN
+            {
+              class module sclass
+              (block
+                (send (const {nil? cbase} {:Class :Module}) :new)
+                args
+                _
+              )
+            }
+          PATTERN
+
+          def in_class_definition?(node)
+            node.each_ancestor(:class, :module, :sclass, :block).any? do |a|
+              class_definition?(a)
+            end
+          end
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/rake/helper/task_definition.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Rake
+      module Helper
+        module TaskDefinition
+          extend NodePattern::Macros
+          extend self
+
+          def_node_matcher :task_or_namespace?, <<-PATTERN
+            (block
+              (send _ {:task :namespace} ...)
+              args
+              _
+            )
+          PATTERN
+
+          def in_task_or_namespace?(node)
+            node.each_ancestor(:block).any? do |a|
+              task_or_namespace?(a)
+            end
+          end
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/rake/method_definition_in_task.rb

@@ -33,49 +33,14 @@ module Rake
       class MethodDefinitionInTask < Cop
         MSG = 'Do not define a method in rake task, because it will be defined to the top level.'
 
-        def_node_matcher :bad_method?, <<~PATTERN
-          (send nil? :bad_method ...)
-        PATTERN
-
-        def_node_matcher :class_definition?, <<~PATTERN
-          {
-            class module sclass
-            (block
-              (send (const {nil? cbase} {:Class :Module}) :new)
-              args
-              _
-            )
-          }
-        PATTERN
-
-        def_node_matcher :task_or_namespace?, <<-PATTERN
-          (block
-            (send _ {:task :namespace} ...)
-            args
-            _
-          )
-        PATTERN
-
         def on_def(node)
-          return if in_class_definition?(node)
-          return unless in_task_or_namespace?(node)
+          return if Helper::ClassDefinition.in_class_definition?(node)
+          return unless Helper::TaskDefinition.in_task_or_namespace?(node)
 
           add_offense(node)
         end
 
         alias on_defs on_def
-
-        private def in_class_definition?(node)
-          node.each_ancestor(:class, :module, :sclass, :block).any? do |a|
-            class_definition?(a)
-          end
-        end
-
-        private def in_task_or_namespace?(node)
-          node.each_ancestor(:block).any? do |a|
-            task_or_namespace?(a)
-          end
-        end
       end
     end
   end

lib/rubocop/cop/rake_cops.rb

@@ -1,4 +1,5 @@
 # frozen_string_literal: true
 
+require_relative 'rake/class_definition_in_task'
 require_relative 'rake/desc'
 require_relative 'rake/method_definition_in_task'

spec/rubocop/cop/rake/class_definition_in_task_spec.rb

@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::Rake::ClassDefinitionInTask do
+  subject(:cop) { described_class.new(config) }
+
+  let(:config) { RuboCop::Config.new }
+
+  it 'registers an offense to a class definition in task' do
+    expect_offense(<<~RUBY)
+      task :foo do
+        class C
+        ^^^^^^^ Do not define a class in rake task, because it will be defined to the top level.
+        end
+      end
+    RUBY
+  end
+
+  it 'registers an offense to a module definition in task' do
+    expect_offense(<<~RUBY)
+      task :foo do
+        module M
+        ^^^^^^^^ Do not define a module in rake task, because it will be defined to the top level.
+        end
+      end
+    RUBY
+  end
+
+  it 'allows class definition in Class.new' do
+    expect_no_offenses(<<~RUBY)
+      task :foo do
+        Class.new do
+          class C
+          end
+        end
+      end
+    RUBY
+  end
+
+  it 'allows class definition outside task' do
+    expect_no_offenses(<<~RUBY)
+      class C
+      end
+
+      task :foo do
+      end
+    RUBY
+  end
+end