updates

config/default.yml

@@ -347,6 +347,13 @@ RSpec/LetSetup:
   VersionAdded: '1.7'
   StyleGuide: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/LetSetup
 
+RSpec/MemoizedHelpersInExampleGroup:
+  Description: Checks if example groups contain too many `let` and `subject` calls.
+  Enabled: false
+  AllowSubject: false
+  Max: 5
+  StyleGuide: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/MemoizedHelpersInExampleGroup
+
 RSpec/MessageChain:
   Description: Check that chains of messages are not being stubbed.
   Enabled: true
@@ -415,12 +422,6 @@ RSpec/NestedGroups:
   VersionChanged: '1.10'
   StyleGuide: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/NestedGroups
 
-RSpec/MemoizedHelpersInExampleGroup:
-  Description: Checks for usage of `let` blocks in specs.
-  Enabled: false
-  AllowSubject: false
-  StyleGuide: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/MemoizedHelpersInExampleGroup
-
 RSpec/NotToNot:
   Description: Checks for consistent method usage for negating expectations.
   Enabled: true

lib/rubocop/cop/rspec/memoized_helpers_in_example_group.rb

@@ -3,29 +3,55 @@
 module RuboCop
   module Cop
     module RSpec
-      # Checks for usage of `let` blocks in specs.
+      # Checks if example groups contain too many `let` and `subject` calls.
       #
-      # This cop can be configured with the option `AllowSubject` which
-      # will configure the cop to only register offenses on explicit calls to
-      # `let` and not calls to `subject`
+      # This cop is configurable using the `Max` option and the `AllowSubject`
+      # which will configure the cop to only register offenses on calls to
+      # `let` and not calls to `subject`.
       #
       # @example
       #   # bad
       #   describe MyClass do
       #     let(:foo) { [] }
-      #     it { expect(foo).to be_empty }
+      #     let(:bar) { [] }
+      #     let!(:booger) { [] }
+      #     subject { {} }
+      #     subject(:wat) { {} }
+      #     subject!(:boo) { {} }
       #   end
       #
       #   describe MyClass do
-      #     subject(:foo) { [] }
-      #     it { expect(foo).to be_empty }
+      #     let(:foo) { [] }
+      #     let(:bar) { [] }
+      #
+      #     context 'when stuff' do
+      #       let!(:booger) { [] }
+      #       subject { {} }
+      #       subject(:wat) { {} }
+      #       subject!(:boo) { {} }
+      #     end
       #   end
       #
       #   # good
       #   describe MyClass do
-      #     it do
-      #       foo = []
-      #       expect(foo).to be_empty
+      #     let(:foo) { [] }
+      #     let!(:booger) { [] }
+      #     subject { {} }
+      #     subject(:wat) { {} }
+      #     subject!(:boo) { {} }
+      #   end
+      #
+      #   describe MyClass do
+      #     context 'when stuff' do
+      #       let(:foo) { [] }
+      #       let(:bar) { [] }
+      #       let!(:booger) { [] }
+      #     end
+      #
+      #     context 'when other stuff' do
+      #       subject { {} }
+      #       subject(:wat) { {} }
+      #       subject!(:boo) { {} }
       #     end
       #   end
       #
@@ -38,39 +64,69 @@ module RSpec
       #   # bad
       #   describe MyClass do
       #     let(:foo) { [] }
-      #     it { expect(foo).to be_empty }
+      #     let(:bar) { [] }
+      #     let!(:booger) { [] }
+      #     let(:subject) { {} }
+      #     let(:wat) { {} }
+      #     let!(:boo) { {} }
       #   end
       #
       #   # good
       #   describe MyClass do
-      #     subject(:foo) { [] }
-      #     it { expect(foo).to be_empty }
+      #     let(:foo) { [] }
+      #     let(:bar) { [] }
+      #     let!(:booger) { [] }
+      #     subject { {} }
+      #     subject(:wat) { {} }
+      #     subject!(:boo) { {} }
+      #   end
+      #
+      # @example with Max configuration
+      #
+      #   # rubocop.yml
+      #   # RSpec/MemoizedHelpersInExampleGroup:
+      #   #   Max: 0
+      #
+      #   # bad
+      #   describe MyClass do
+      #     let(:foo) { [] }
       #   end
       #
+      #   # good
       #   describe MyClass do
-      #     it do
-      #       foo = []
-      #       expect(foo).to be_empty
-      #     end
+      #     def foo; []; end
       #   end
       #
       class MemoizedHelpersInExampleGroup < Cop
-        MSG = 'Avoid using `%<method>s` ' \
-              '– use a method call or local variable instead.'
+        MSG = 'Example has too many memoized helpers [%<count>d/%<max>d]'
 
-        def_node_matcher :let?, Helpers::ALL.send_pattern
-        def_node_matcher :subject?, Subject::ALL.send_pattern
+        def on_block(node)
+          return unless spec_group?(node)
 
-        def on_send(node)
-          if subject?(node) && !allow_subject?
-            add_offense(node, message: format(MSG, method: 'subject'))
-          elsif let?(node)
-            add_offense(node, message: format(MSG, method: 'let'))
+          count = count_helpers(node)
+
+          node.each_ancestor(:block) do |ancestor|
+            count += count_helpers(ancestor)
           end
+
+          return if count <= max
+
+          add_offense(node, message: format(MSG, count: count, max: max))
         end
 
         private
 
+        def count_helpers(node)
+          example_group = RuboCop::RSpec::ExampleGroup.new(node)
+          count = example_group.lets.count
+          count += example_group.subjects.count unless allow_subject?
+          count
+        end
+
+        def max
+          cop_config['Max']
+        end
+
         def allow_subject?
           cop_config['AllowSubject']
         end

lib/rubocop/cop/rspec_cops.rb

@@ -59,6 +59,7 @@
 require_relative 'rspec/leaky_constant_declaration'
 require_relative 'rspec/let_before_examples'
 require_relative 'rspec/let_setup'
+require_relative 'rspec/memoized_helpers_in_example_group'
 require_relative 'rspec/message_chain'
 require_relative 'rspec/message_expectation'
 require_relative 'rspec/message_spies'
@@ -68,7 +69,6 @@
 require_relative 'rspec/multiple_subjects'
 require_relative 'rspec/named_subject'
 require_relative 'rspec/nested_groups'
-require_relative 'rspec/no_let'
 require_relative 'rspec/not_to_not'
 require_relative 'rspec/overwriting_setup'
 require_relative 'rspec/pending'

manual/cops.md

@@ -58,6 +58,7 @@
 * [RSpec/LeakyConstantDeclaration](cops_rspec.md#rspecleakyconstantdeclaration)
 * [RSpec/LetBeforeExamples](cops_rspec.md#rspecletbeforeexamples)
 * [RSpec/LetSetup](cops_rspec.md#rspecletsetup)
+* [RSpec/MemoizedHelpersInExampleGroup](cops_rspec.md#rspecmemoizedhelpersinexamplegroup)
 * [RSpec/MessageChain](cops_rspec.md#rspecmessagechain)
 * [RSpec/MessageExpectation](cops_rspec.md#rspecmessageexpectation)
 * [RSpec/MessageSpies](cops_rspec.md#rspecmessagespies)
@@ -67,7 +68,6 @@
 * [RSpec/MultipleSubjects](cops_rspec.md#rspecmultiplesubjects)
 * [RSpec/NamedSubject](cops_rspec.md#rspecnamedsubject)
 * [RSpec/NestedGroups](cops_rspec.md#rspecnestedgroups)
-* [RSpec/MemoizedHelpersInExampleGroup](cops_rspec.md#rspecnolet)
 * [RSpec/NotToNot](cops_rspec.md#rspecnottonot)
 * [RSpec/OverwritingSetup](cops_rspec.md#rspecoverwritingsetup)
 * [RSpec/Pending](cops_rspec.md#rspecpending)